Debris monitoring

ABSTRACT

A debris monitoring system includes a receptacle, a first and a second emitter, and a first receiver. The receptacle defines an opening to receive debris into the receptacle. The first and second emitter are each arranged to emit a signal across at least a portion of the opening. The first receiver is proximate to the first emitter to receive reflections of the signal emitted by the first emitter, and the first receiver is disposed toward the opening to receive an unreflected portion of the signal emitted by the second emitter across at least a portion of the opening.

CLAIM OF PRIORITY

This U.S. patent application is a continuation of and claims priority toU.S. patent application Ser. No. 13/340,784, filed on Dec. 30, 2011which claims priority under 35 U.S.C. §119(e) to U.S. ProvisionalApplication 61/428,808, filed on Dec. 30, 2010, the disclosure of eachof which are considered part of the disclosure of this application andare hereby incorporated by reference in its entirety.

TECHNICAL FIELD

This application relates to robots, and more particularly to autonomouscoverage robots.

BACKGROUND

Autonomous robots can perform desired tasks in unstructured environmentswithout continuous human guidance. Many kinds of robots are autonomousto some degree. Different robots can be autonomous in different ways. Anautonomous coverage robot can traverse a work surface without continuoushuman guidance to perform one or more tasks. In the field of home,office and/or consumer-oriented robotics, mobile robots that performhousehold functions such as removing debris from a surface (e.g., vacuumcleaning and floor washing) have been widely adopted.

SUMMARY

In one aspect, a debris monitoring system includes a receptacle, a firstand a second emitter, and a first receiver. The receptacle defines anopening to receive debris into the receptacle. The first and secondemitter are each arranged to emit a signal across at least a portion ofthe opening. The first receiver is proximate to the first emitter toreceive reflections of the signal emitted by the first emitter, and thefirst receiver is disposed toward the opening to receive an unreflectedportion of the signal emitted by the second emitter across at least aportion of the opening.

In another aspect, a coverage robot includes a housing, a drive system,a cleaning assembly, a receptacle, a first and a second emitter, and afirst receiver. The drive system is coupled to the housing andconfigured to maneuver the robot across a cleaning surface. The cleaningassembly is coupled to the housing. The receptacle is disposedsubstantially within the housing, and the receptacle defines an openingto receive debris into the receptacle from the cleaning assembly. Thedebris monitoring system is disposed substantially within the housing.The debris monitoring system includes a first and a second emitter and afirst receiver. The first and second emitter are each arranged to emit asignal across at least a portion of the opening. The first receiverproximate to the first emitter to receive reflections of the signalemitted by the first emitter and the first receiver disposed toward theopening to receive an unreflected portion of the signal emitted by thesecond emitter across at least a portion of the opening.

Implementations of one or more of these aspects of the disclosure mayinclude one or more of the following features. In some implementations,the first receiver and the second emitter are disposed substantiallyopposite one another across the largest dimension of the opening. Theopening can be substantially rectangular. Additionally or alternatively,the first receiver and the second receiver can be substantiallydiagonally opposed to one another across the opening. In certainimplementations, the first and second emitters are arranged relative toone another such that the respective signals emitted by the first andsecond emitters intersect along at least a portion of the opening. Theopening can be defined in a substantially vertical plane as debris isreceived into the receptacle.

In certain implementations, the opening has a top portion and a bottomportion, the top portion above the bottom portion as debris is receivedinto the receptacle, and the first and second emitters and the firstreceiver each disposed toward a top portion of the opening, with thefirst receiver disposed above the first and second emitters.

In some implementations, the first receiver is arranged about 0.5 inchesto about 30 inches from the second emitter. The first receiver can beless than about 5 inches from the first emitter. Additionally oralternatively, the ratio of the distance between the first receiver andthe second emitter to the distance between the first receiver and thefirst emitter is about 0.1 to about 600.

In certain implementations, the receptacle is releasably engageable witha housing configured to support the receptacle as debris is receivedthrough the opening of the receptacle. The first and second emitters andthe first receiver can each be supported on the housing and thereceptacle can be movable relative to the first and second emitters andthe first receiver. The first and second emitters and the first receivercan each be supported on the receptacle. A controller can be supportedon the housing. The first and second emitters and the first receiver caneach be in wireless communication (e.g., infrared communication) withthe controller.

In some implementations, the receptacle is removable from a side portionof the coverage robot when the robot is on the cleaning surface and/orremovable from a side portion of the housing. Additionally oralternatively, the receptacle is removable from a top portion of thecoverage robot when the robot is on the cleaning surface and/orremovable from a top portion of the housing.

In another aspect, a debris monitoring system includes a receptacle, aplurality of first emitters and a plurality of second emitters, a firstreceiver, and a second receiver. The receptacle defines an opening toreceive debris into the receptacle. Each emitter of each plurality ofemitters is arranged to emit a signal across at least a portion of theopening. The first receiver is proximate to the plurality of firstemitters to receive reflections of the signal emitted by each of theplurality of first emitters and the first receiver is disposed towardthe opening to receive an unreflected portion of the signal emitted byeach of the plurality of second emitters across at least a portion ofthe opening. The second receiver is proximate to the plurality of secondemitters to receive reflections of the signal emitted by each of theplurality of second emitters and the second receiver disposed toward theopening to receive an unreflected portion of the signal emitted by eachof the plurality of first emitters across at least a portion of theopening.

Implementations of this aspect of the disclosure may include one or moreof the following features. In some implementations, a controller isconfigured to pulse the plurality of first emitters on and off and topulse the plurality of second emitters on and off. The controller can beconfigured to sample of each of the first and second receiverssynchronously such that a first sample of each receiver is taken whenthe plurality of first emitters and the plurality of second emitters areoff, a second sample of each receiver is taken when the plurality offirst emitters is on and the plurality of second emitters is off, and athird sample of each receiver is taken when the plurality of firstemitters is off and the plurality of second emitters is on.

In certain implementations, the plurality of first emitters and theplurality of second emitters are arranged relative to one another suchthat the signals emitted by the plurality of first emitters intersectthe signals emitted by the plurality of second emitters. Theintersection can be along at least a portion of the opening. Theplurality of first emitters and the plurality of second emitters can bearranged relative to one another such that the signals emitted by theplurality of first emitters intersect the signals emitted by theplurality of second emitters along a line substantially bisecting theopening.

In some implementations, the plurality of first emitters and theplurality of second emitters are spaced relative to one another suchthat the signals emitted by the plurality of first emitters and theplurality of second emitters span substantially all (e.g., more than 50percent) of the area of the opening when all of the emitters from eachof the plurality of first and second emitters are on.

In yet another aspect, a debris monitoring method includes activatingand deactivating a first emitter and a second emitter, measuring a firstreceiver disposed proximate to the first emitter, and detecting movementof debris through the opening. The first emitter and the second emitterare activated to emit respective signals at a substantially constantfrequency across an opening defined by a receptacle. The first receiveris disposed proximate to the first emitter to receive a reflectedportion of the signal from the first emitter and disposed relative tothe second emitter to receive an unreflected portion of the signal fromthe second emitter. The detection of movement of debris through theopening is based at least in part on a first measurement obtained whenthe first and second emitters are each deactivated, a second measurementobtained when the first emitter is activated and the second emitter isdeactivated, and a third measurement is obtained when the first emitteris deactivated and the second emitter is activated.

Implementations of this aspect of the disclosure may include one or moreof the following features. In some implementations, detecting movementof debris through the opening includes processing the first, second, andthird measurements as a function of time and detecting changes in atleast one of the processed second and third measurements. In certainimplementations, detecting movement of debris through the openingincludes filtering ambient light from the second and third measurementsbased at least in part on the first measurement. The first, second, andthird measurements can be processed as a function of time (e.g., by lowpass filtering at least one of the second and third measurements). Insome implementations, detecting changes in at least one of the processedsecond and third measurements includes comparing the instantaneouschange to an average value of the respective processed measurement.

In certain implementations, the debris monitoring method includesdetermining the amount of light blocked by debris passing through theopening and periodically assigning a score to the debris based at leastin part on the determined amount of light blocked by the debris.Determining the amount of light blocked by debris passing through theopening can be based at least in part the second or third measurement.

In some implementations, the debris monitoring method includes summingconsecutive debris scores and providing a dirt detection signal if thesum of the debris scores exceeds a threshold value. The sum of thedebris score can be decremented over time. The amount of the decrementcan be based at least in part on a running average value of the debrisscores.

In still another aspect, a debris monitoring method including activatingand deactivating a first emitter and a second emitter to emit respectivesignals across an opening defined by a receptacle, measuring a firstreceiver, and determining whether a receptacle is full of debris. Thefirst receiver is disposed proximate to the first emitter to receive areflected portion of the signal from the first emitter and disposedrelative to the second emitter to receive an unreflected portion of thesignal from the second emitter. The determination of whether thereceptacle is full of debris is based at least in part on comparing afirst reflective signal to a first transmissive signal. The firstreflective signal is derived from a measurement by the first receiverwhen the first emitter is activated and the second emitter isdeactivated and first transmissive signal derived from a measurement bythe first receiver when the first emitter is deactivated and the secondemitter is activated.

Implementations of this aspect of the disclosure may include one or moreof the following features. In some implementations, determining whethera receptacle is full of debris includes setting a first threshold basedat least in part on a comparison of the first reflective signal to thefirst transmissive signal. The first threshold can be set based in parton the first reflective signal and the first transmissive signalreaching a first crossover point at which the first reflective signalchanges from being less than the first transmissive signal to beinggreater than or equal to the first transmissive signal. The firstthreshold can be set to a value greater than the value of the firstreflective signal at the first crossover point. Additionally oralternatively, the first threshold value can be based at least in parton one or more of the following: the value of the first crossover pointand the rate at which the first reflective signal reached the firstcrossover point. The first threshold can be reset if the firstreflective signal falls below the first crossover point after thethreshold has been set.

In some implementations, the debris monitoring method includesdecrementing the threshold over time until the first reflective signalis greater than the first threshold. In certain implementations, thedebris monitoring method includes generating a receptacle-full signal ifthe first reflective signal and the first transmissive signal are eachabout zero.

In some implementations, the debris monitoring method includes measuringa second receiver disposed proximate to the second emitter to receive areflected portion of the signal from the second emitter and disposedrelative to the first emitter to receive an unreflected portion of thesignal from the second emitter. Determining whether a receptacle is fullof debris can include comparing a second reflective signal, derived froma measurement by the second receiver when the second emitter isactivated and the first emitter is deactivated, to a second transmissivesignal, derived from a measurement by the second receiver when thesecond emitter is deactivated and the first emitter is activated.Determining whether a receptacle is full of debris can include setting asecond threshold based at least in part on a comparison of the secondreflective signal to the second transmissive signal. Additionally oralternatively, the debris monitoring method includes generating areceptacle-full signal if the first and second reflective signals eachexceed the respective first and second thresholds.

In yet another aspect, a debris monitoring method includes maneuveringan autonomous coverage robot across a cleaning surface, activating anddeactivating a first emitter and a second emitter, measuring a firstreceiver, receiving a signal from the first receiver, detecting movementof the debris through the opening based at least in part on the receivedsignal, and determining whether a receptacle is full of debris based atleast in part on the received signal. The robot carries a cleaningassembly and the receptacle arranged relative to the cleaning assemblyto receive debris removed from the cleaning surface by the cleaningassembly. The first and second emitter are activated and deactivated toemit respective signals across an opening defined by the receptacle. Thefirst receiver is disposed proximate to the first emitter to receive areflected portion of the signal from the first emitter and disposedrelative to the second emitter to receive an unreflected portion of thesignal from the second emitter. Receiving the signal from the firstreceiver includes receiving a dark signal derived from a measurement bythe first receiver when the first emitter is deactivated and the secondemitter is deactivated, receiving a reflective signal derived from ameasurement by the first receiver when the first emitter is activatedand the second emitter is deactivated, and receiving a transmissivesignal derived from a measurement by the first receiver when the firstemitter is deactivated and the second emitter is activated. Detectingmovement of debris through the opening is based at least in part on thedark signal, the reflective signal, and the transmissive signal, anddetermining whether a receptacle is full of debris is based at least inpart on the reflective signal and the transmissive signal.

Implementations of this aspect of the disclosure may include one or moreof the following features. In some implementations, movement of therobot is altered based at least in part upon detecting movement ofdebris through the opening. Altering movement of the robot can includeinitiating a spot coverage cleaning pattern. For example, initiating aspot coverage cleaning pattern can include immediately altering thedirection of travel of the robot toward the detected debris. The spotcoverage pattern can include one or more of the following: a spiralpattern, a star pattern, and a cornrow pattern. In some implementations,at least one dimension of the spot coverage pattern is at least partlybased on a change in detected movement of debris through the opening.Additionally or alternatively, altering movement of the robot includeschanging at least one of the following: direction of travel of the robotand speed of travel of the robot.

In certain implementations, the debris monitoring method includesaltering movement of the robot based at least in part upon determiningthat the receptacle is full of debris. Altering movement of the robotcan include moving the robot toward an evacuation station configured toengage the receptacle. In some implementations, the debris monitoringmethod includes deactivating the cleaning assembly based at least inpart upon determining that the receptacle is full of debris.

In still another aspect, an autonomous coverage robot includes a robotbody having a forward portion and a rear portion, right and left drivenwheels, a debris agitator carried by the robot body, a first and asecond cliff sensor, and a controller in communication with the rightand left driven wheels and the first and second cliff sensors. The rightand left driven wheels define a transverse axis between the forwardportion and the rear portion of the robot body and each driven wheel isrotatable about the transverse axis. The debris agitator is configuredto remove debris from the cleaning surface. The first cliff sensor isdisposed forward of the transverse axis and the second cliff sensor isdisposed rear of the transverse axis. The controller is configured toalter the direction of travel of the robot based at least in part onsignals received from the first and second cliff sensors.

Implementations of this aspect of the disclosure may include one or moreof the following features. In some implementations, comprising a wastereceptacle carried by the robot body and in fluid communication with thedebris agitator to receive the debris removed from the cleaning surface.At least a portion of the waste receptacle can be disposed within therobot body. Additionally or alternatively, the waste receptacle can becarried on the rear portion of the robot body.

In certain implementations, the waste receptacle is releasablyengageable with the robot body and the second cliff sensor is disposedon the waste receptacle. The controller can be in wireless communicationwith the second cliff sensor, and this wireless communication caninclude one or more of the following: optical communication,electromagnetic communication, and radiofrequency communication.

In some implementations, a first electrical contact is disposed on thewaste receptacle and a second electrical contact is carried on the robotbody, wherein the first electrical contact is releasably engageable withthe second electrical contact to establish electrical communicationbetween the second cliff sensor and the controller. The controller canbe configured to disable the right and left driven wheels ifcommunication with the second cliff sensor is interrupted.

In certain implementations, the autonomous coverage robot includes athird cliff sensor disposed rear of the transverse axis. The third cliffsensor can be proximate to the waste receptacle. Additionally oralternatively, the second cliff sensor is proximate to the wastereceptacle.

In some implementations, the first cliff sensor and the second cliffsensor define a fore-aft axis substantially perpendicular to thetransverse axis. In certain implementations, the debris agitator extendssubstantially parallel to the transverse axis.

In another aspect, a waste receptacle for an autonomous coverage robotfor removing debris from a cleaning surface includes a housingreleasably engageable with a robot body of the autonomous coverage robotand a cliff sensor supported on the housing. The housing defines avolume for containing debris, and the housing defines an opening forreceiving debris removed from the cleaning surface. The cliff sensor isarranged to detect a potential cliff while the housing is releasablyengaged with the robot body and the robot removes debris from thecleaning surface.

Implementations of this aspect of the disclosure may include one or moreof the following features. In some implementations, at least a portionof the housing defines at least a portion of a perimeter of theautonomous coverage robot while the housing is releasably engaged withthe robot body. Additionally or alternatively, at least a portion of thehousing defines at least a portion of a surface of the autonomouscoverage robot substantially opposite the cleaning surface when therobot removes debris from the cleaning surface. In some implementations,at least a portion of the housing defines at least a portion of asurface of the autonomous coverage robot substantially perpendicular tothe cleaning while the robot removes debris from the cleaning surface.

In certain implementations, the cliff sensor is supported on the portionof the housing defining at least a portion of the perimeter of theautonomous coverage robot. The housing can have a substantially arcuateportion and the cliff sensor can be disposed along the substantiallyarcuate portion. The substantially arcuate portion can be opposite theopening for receiving debris removed from the cleaning surface.

In some implementations, the housing has a dimension of less than aboutten inches in a direction substantially perpendicular to the cleaningsurface when the housing is releasably engaged with the robot body andthe robot removes debris from the cleaning surface.

In certain implementations, an electrical contact is supported on thehousing and in electrical communication with the cliff sensor, theelectrical contact configured for releasable engagement with anelectrical contact supported on the robot body. In some implementations,an optical emitter supported on the housing and in electricalcommunication with the cliff sensor, the optical emitter configured foroptical communication with an optical receiver supported on the robotbody.

In another aspect, a method of maneuvering an autonomous coverage robotincludes receiving a signal from a first cliff sensor, receiving asignal from a second cliff sensor, and driving the right and left drivenwheels to move the robot in a direction substantially opposite adetected potential cliff. The first cliff sensor is arranged to detect apotential cliff forward of a transverse axis defined by right and leftdriven wheels of the robot. The transverse axis is substantiallyperpendicular to the fore-aft direction of travel of the robot. Thesecond cliff sensor is arranged to detect a potential cliff aft of thetransverse axis.

Implementations of this aspect of the disclosure may include one or moreof the following features. In some implementations, receiving the signalfrom the second cliff sensor includes receiving a wireless signal fromthe second cliff sensor. Additionally or alternatively, receiving thesignal from the second cliff sensor includes receiving at least aportion of the signal through a releasably engageable electricalcontact.

In certain implementations, the first cliff sensor is disposed along thesubstantially forward-most portion of the robot and the second cliffsensor is disposed along the substantially rear-most portion of therobot. In some implementations, whether the second cliff sensor ispresent is determined and the right and left driven wheels are disabledif the second cliff detector is not present. In certain implementations,driving the right and left driven wheels to move the robot in adirection substantially opposite a detected potential cliff includesmoving the robot a distance greater than the distance between the rightand left drive wheels along the transverse axis.

In yet another aspect, a method of operating an autonomous cleaningapparatus includes controlling a drive system of the cleaning apparatusto move the cleaning apparatus over a cleaning surface, receiving asignal from a debris sensor of the cleaning apparatus, and moving thecleaning apparatus through a pattern of movement based at least in parton the received debris signal. The signal from the debris sensorindicates that the cleaning apparatus is collecting debris. The patternof movement includes a plurality of swaths.

Implementations of this aspect of the disclosure may include one or moreof the following features. In some implementations, each of theplurality of swaths is substantially parallel to one another. In certainimplementations, each of the plurality of swaths extends from a centralregion in a star pattern. The central region can be an area of thecleaning surface corresponding substantially to a local maximum of thereceived debris signal. The star pattern can radiate through an angle ofabout 360 degrees.

In certain implementations, at least a portion of at least some of theplurality of swaths overlap one another. In some implementations, theamount of overlap between swaths can be adjusted based at least in parton the magnitude of the debris signal. Additionally or alternatively,the number of swaths can be based at least in part on the signal fromthe debris sensor. In certain implementations, adjusting the number ofswaths includes adjusting the number of swaths in proportion themagnitude of the debris signal.

In some implementations, the length of each swath is adjusted based atleast in part on the signal from the debris sensor. Additionally oralternatively, each swath can be terminated when the debris signal fallsbelow a threshold. In certain implementations, the debris sensor is anoptical sensor disposed in a cleaning pathway of the cleaning apparatus.The debris sensor can include an optical sensor disposed on a wastereceptacle releasably engageable with the cleaning apparatus.Additionally or alternatively, debris sensor comprises a piezoelectricsensor element.

In another aspect, a method of operating an autonomous cleaningapparatus includes controlling a drive system of the cleaning apparatusto move the cleaning apparatus over a cleaning surface, receiving asignal from a debris sensor of the cleaning apparatus, moving thecleaning apparatus along the heading in the direction of the detecteddebris. The signal corresponds to a heading in the direction of detecteddebris.

Implementations of this aspect of the disclosure may include one or moreof the following features. In some implementations, the debris sensorincludes a camera directed substantially forward of the cleaningapparatus. In certain implementations, the camera is movable to scan anarea substantially forward of the cleaning apparatus. Additionally oralternatively, the size of the debris is determined and the cleaningapparatus is moved away from debris larger than a threshold size.

In another aspect, a method of navigating an autonomous coverage robotincludes maneuvering an autonomous coverage robot over a surface,detecting a first change in a signal emitted from a maintenance stationconfigured to receive the autonomous coverage robot, detecting a secondchange in the signal from the maintenance station, and determining theprobability that the robot will find the maintenance station in a periodof time. The determined probability is based at least in part on anelapsed time between the detected first change in the signal and thedetected second change in the signal.

Implementations of this aspect of the disclosure may include one or moreof the following features. In some implementations, determining theprobability that the robot will find the maintenance station in theperiod of time includes updating a probability distribution based atleast in part on the elapsed time. The probability distribution can be anon-parametric model (e.g., a histogram). Additionally or alternatively,the probability distribution can be a parametric model, such as aPoisson distribution in which the mean of the Poisson distribution isestimated (e.g., as an average).

In some implementations, the method of navigating an autonomous coveragerobot further includes determining the probability that power availablefrom a battery carried by the robot will be depleted before the robotcan find the maintenance station. In certain implementations, a periodof time is allotted for finding the maintenance station. The allottedperiod of time can be based at least in part on the determinedprobability that the robot will find the maintenance station in theallotted period of time. In some examples, the power to the robot isreduced during the allotted period of time. For example, reducing thepower can include reducing power to a cleaning assembly carried by therobot.

In certain implementations, the method of navigating an autonomouscoverage robot further includes detecting whether the robot has beenremoved from the surface and ignoring the detected first change in thesignal occurring just prior to detection that the robot has been removedfrom the surface and ignoring the detected second change in the signaloccurring just after detection that the robot has been removed from thesurface. For example, detecting that the robot has been removed from thesurface can include receiving a signal from one or more sensors (e.g.,wheel drop sensors and/or cliff detectors) carried by the robot.

In certain implementations, releasable contact between the robot and themaintenance station is established. Upon establishing releasable contactbetween the robot and the maintenance station, a battery carried by therobot can be charged.

In yet another aspect, a method of navigating an autonomous coveragerobot includes maneuvering an autonomous coverage robot over a surface,detecting a first structure disposed along the surface, detecting asecond structure disposed along the surface, determining the probabilitythat the robot will find the first structure in a period of time,wherein the determined probability is based at least in part ondetecting the second structure and an elapsed time between the detectingthe first structure and detecting the second structure.

Implementations of this aspect of the disclosure may include one or moreof the following features. The first structure can be a maintenancestation configured to receive the robot and the second structure is alighthouse. Additionally or alternatively, the first structure can be afirst lighthouse and the second structure is a second lighthouse.

In still another aspect, a system includes a maintenance station and anautonomous coverage robot. The maintenance station includes an emitterfor emitting a signal. The autonomous coverage robot is configured tomaneuver over a surface and includes at least one receiver for receivingthe emitted signal and a controller. The controller configured tomaneuver the robot across the surface, detect a first change in a signalemitted from the maintenance station and received by the at least onereceiver, detect a second change in the signal from the maintenancestation and received by the at least one receiver and determine theprobability that the robot will find the maintenance station in a periodof time. The determined probability is based at least in part on anelapsed time between the detected first change in the signal and thedetected second change in the signal.

Implementations of this aspect of the disclosure may include one or moreof the following features. The emitter can include an infrared emitterand the at least one receiver comprises an infrared receiver. In someimplementations, the autonomous coverage robot further includes abattery. The maintenance station can be configured to releasably engagethe autonomous coverage robot to transfer power to the battery.

In yet another aspect, a method of calibrating a debris monitoringsystem of a waste receptacle includes detecting an initiation condition,applying a first pulse width modulation duty cycle to an emitter array,measuring a first signal at a receiver in response to the first pulsewidth modulation cycle, applying a second pulse width modulation dutycycle to an emitter array, measuring a second signal at the receiver inresponse to the second pulse width modulation duty cycle, determiningwhether the difference between the measured first signal and themeasured signal is greater than the threshold, and setting the measuredsecond signal as a base brightness based at least in part on thedetermination of whether the difference between the measured firstsignal and the measured second signal is greater than the threshold. Thesecond pulse width modulation duty cycle is less than the first pulsewidth modulation duty cycle.

Implementations of this aspect of the disclosure may include one or moreof the following features. Detecting the initiation condition caninclude detecting insertion of the waste receptacle into the body of adebris collection device (e.g., an autonomous cleaning robot).Additionally or alternatively, detecting the initiation condition caninclude detecting applied power (e.g., detecting insertion of a batteryand/or the position of a power switch). In some implementations, anindicator is activated based at least in part on detecting theinitiation condition.

In certain implementations, the indicator is deactivated based at leastin part on whether the difference between the measured first signal andthe measured second signal is greater than the threshold.

In some implementations, activating and/or deactivating the indicatorincludes activating and/or deactivating one or more light-emittingdiodes.

In certain implementations, applying the first pulse width modulationduty cycle to the emitter array includes applying a maximum pulse widthmodulation duty cycle to the emitter array.

In some implementations, the waste receptacle defines an opening toreceive debris into the waste receptacle. The first emitter array can bearranged to emit a signal across at least a portion of the opening.Measuring the first and second signals at the receiver can each includereceiving an unreflected portion of the signal emitted by the firstemitter. Additionally or alternatively, measuring the first and secondsignals at the receiver can each include receiving a reflected portionof the signal emitted by the first emitter.

In certain implementations, applying the second pulse width modulationduty cycle to the emitter array includes determining whether the appliedsecond pulse width modulation is greater than a limit value.

In still another aspect, a debris monitoring system includes areceptacle, a plurality of first emitters and a plurality of secondemitters, a first receiver, and a second receiver. The receptacleincludes a barrier extending horizontally across a width of thereceptacle and extending vertically along at least a portion of a heightof the receptacle, the barrier defining at least a portion of an openingto receive debris into the receptacle. The first emitters are verticallyspaced apart from one another on a first side of the opening, and thesecond emitters are vertically spaced apart from one another on a secondside of the opening. The emitters of the first and second emitters arearranged to emit a signals span the horizontal and vertical dimensionsof the opening. The first receiver is proximate to the plurality offirst emitters. The second receiver is proximate to the plurality ofsecond emitters.

In some implementations, the at least a portion of the barrier is a doormovable to allow access to debris stored in the receptacle. For example,the barrier can include a hinged door. Additionally or alternatively,the barrier can include a slidable door.

In certain implementations, a vertical dimension of the opening issubstantially ½ or less of the combined height of the receptacle (e.g.,substantially ½ or less of the combined height of the barrier and avertical dimension of the opening).

In some implementations, a width of the opening can be about ⅔ or lessof a width of the receptacle. In these implementations, the barrier canextend substantially across the entire width of the receptacle. Thus,for example, the width of the barrier can be at least ⅓ greater than thewidth of the opening.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1A is a top view of an autonomous robotic cleaner.

FIG. 1B is a bottom view of an autonomous robotic cleaner.

FIG. 1C is a side view of an autonomous robotic cleaner.

FIG. 2 is a block diagram of systems of an autonomous robotic cleaner.

FIGS. 3A-3B are top views of autonomous robotic cleaners.

FIG. 3C is a rear perspective view of an autonomous robotic cleaner.

FIGS. 3D-3E are bottom views of autonomous robotic cleaners.

FIGS. 3F-3G are perspective views of an autonomous robotic cleaner.

FIGS. 4A-4B are perspective views of removable cleaning bins.

FIGS. 4C-4E are schematic views an autonomous robotic cleaner.

FIG. 5A is a top view of an autonomous robotic cleaner.

FIG. 5B is a top view of a bin sensor brush.

FIGS. 6A-6C are schematic views of autonomous robotic cleaners.

FIGS. 7A-7B are front views of removable cleaning bins.

FIGS. 7C-7E are perspective views of removable cleaning bins.

FIGS. 7F-7H are front views of removable cleaning bins.

FIGS. 8A-8E are front views of removable cleaning bins.

FIG. 9A is process flow chart of a debris monitoring routine.

FIG. 9B is a process flow chart of a debris quantifying routine.

FIG. 9C is a process flow chart of a bin-full detection routine.

FIG. 9D is a process flow chart of a threshold setting routine.

FIG. 9E is a process flow chart of a calibration routine

FIG. 10A is a schematic of a robot cleaning pattern.

FIG. 10B is a schematic of a robot cleaning pattern.

FIG. 11 is a perspective view of a robot.

FIGS. 12A-12B are schematic views of autonomous robotic cleaners.

FIG. 13A is a perspective view of a cleaning bin.

FIGS. 13B-13D are schematic views of cleaning bin indicators.

FIG. 14A is a schematic view of a cleaning bin indicator system.

FIGS. 14B-14C are schematic views of remote cleaning bin indicators.

FIG. 14D is a schematic view of an autonomous robotic cleaner and anevacuation station.

FIG. 15A is a schematic view of an autonomous robotic cleaner and anevacuation station.

FIG. 15B is a schematic view of an autonomous robotic cleaner movingrelative to an evacuation station.

FIG. 16 is a process flow chart of a seeking routine.

FIG. 17 is a schematic view of an autonomous robotic cleaner movingrelative to an evacuation and a second structure.

FIG. 18 is a process flow chart of a seeking routine.

FIG. 19A is a partially exploded, top perspective view of an autonomousrobotic cleaner.

FIG. 19B is a partially exploded, bottom perspective view of theautonomous robotic cleaner of FIG. 19A.

FIG. 19C is a cross-sectional front view of the autonomous roboticcleaner of FIG. 19A in an unexploded configuration, taken along the line19C-19C.

FIG. 19D is a perspective view of the dust bin of the autonomous roboticcleaner of FIG. 19A.

FIG. 19E is a side view of the dust bin of the autonomous roboticcleaner of FIG. 19A.

FIG. 19F is a cross-section of the dust bin of the autonomous roboticcleaner of FIG. 19A, taken along the line 19F-19F.

FIG. 19G is a cross-section of the dust bin of the autonomous roboticcleaner of FIG. 19A, taken along the line 19G-19G.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Referring to FIGS. 1A-1C, an autonomous robotic cleaner 11 includes arobot body 31 (e.g., a chassis and/or housing) which carries an outershell 6 connected to a bumper 5. The robot body 31 also carries acontrol panel 10 and an omnidirectional receiver 15, which has a 360degree line of vision for detection of signals emitted towards the robot11 from substantially all directions.

Referring to FIG. 1B, installed along either side of the robot body 31are differentially driven wheels 45, each rotatable about a transverseaxis, to mobilize the robot 11 and provide two points of support. Thedifferentially driven wheels 45 may move the robot 11 in forward andreverse drive directions such that the robot body 31 has a correspondingforward portion 31A forward of the differentially driven wheels 45 and arear portion 31B rear of the differentially driven wheels 45.

Cliff sensors 30A (e.g., infrared sensors) are installed on theunderside of the robot 11, along the forward portion 31A of the robotbody 31, to detect a potential cliff forward of the robot 11 as therobot 11 moves in the forward drive direction. Cliff sensors 30B areinstalled on the underside of the robot 11, along the rear portion 31Bof the robot body 31, to detect a potential cliff rear of the robot 11as the robot 11 moves in the reverse drive direction. At least one ofthe cliff sensors 30B is disposed on a debris bin 50 in fluidcommunication with a cleaning head 40 to receive debris removed from acleaning surface. The cliff sensor 30B disposed on the cleaning bin 50can be in communication with one or more components on the robot body 31and/or powered by a source on the robot body 31 through a communicationand/or power channel, each described below, established between thecleaning bin 50 and the robot body 31. The cliff sensors 30A,B areconfigured to detect sudden changes in floor characteristics indicativeof an edge or cliff of the floor (e.g. an edge of a stair). As describedin further detail below, cliff sensors 30A and 30B can facilitateexecution of a cleaning pattern including back and forth motion of therobot 11 over an area containing debris. For example, cliff sensors30A,B disposed forward and rear of the robot 11 can reduce thelikelihood that the robot 11 would move over a cliff forward or rearwardof the robot 11 as the robot moves back and forth during execution of acleaning pattern.

The forward portion 31A of the chassis 31 includes a caster wheel 35which provides additional support for the robot 11 as a third point ofcontact with the floor and does not hinder robot mobility. Locatedproximate to and on either side of the caster wheel 35 are twowheel-floor proximity sensors 70. The wheel-floor proximity sensors 70are configured to detect sudden changes in floor characteristicsindicative of an edge or cliff of the floor (e.g. an edge of a stair).The wheel-floor proximity sensors 70 provide redundancy should theprimary cliff sensors 30A fail to detect an edge or cliff. In someimplementations, the wheel-floor proximity sensors 70 are not included,while the primary cliff sensors 30A remain installed along the bottomforward portion 31A of the chassis 31. In certain implementations, thecaster wheel 35 is not included and additional support for the robot 11is provided by at least a portion of the cleaning head assemblydescribed in detail below.

A cleaning head assembly 40 is disposed generally between the forwardportion 31A and the rear portion 31B of the robot 11, with at least aportion of the cleaning head assembly disposed within the robot body 31.The cleaning head assembly 40 includes a main 65 brush and a secondarybrush 60. A battery 25 is carried on the robot body 31 and, in someimplementations, is proximate the cleaning head assembly 40. In someexamples, the main 65 and/or the secondary brush 60 are removable. Inother examples, the cleaning head assembly 40 includes a fixed mainbrush 65 and/or secondary brush 60, where fixed refers to a brushpermanently installed on the robot body 31.

A side brush 20 is supported on one side of the robot body 31 such atleast a portion of the side brush 20 extends beyond the robot body 31.In some implementations, the side brush 20 is configured to rotate 360degrees, about an axis substantially perpendicular to the cleaningsurface, when the robot 11 is operational. The rotation of the sidebrush 20 may improve cleaning in areas adjacent the robot's side, andareas (e.g., corners) otherwise unreachable by the more centrallylocated cleaning head assembly 40.

A removable cleaning bin 50 is supported towards the back end 31B of therobot 11, with at least a portion of the removable cleaning bin disposedwithin the outer shell 6. In certain implementations, the cleaning bin50 is removable from the chassis 31 to provide access to bin contentsand an internal filter 54. Additionally or alternatively, access to thecleaning bin 50 may be provided via an evacuation port 80, as shown inFIG. 1C. In some implementations, the evacuation port 80 includes a setof sliding side panels 55 which slide along a side wall of the chassis31 and under side panels of the outer shell 6 to open the evacuationport 80. The evacuation port 80 is configured to mate with correspondingevacuation ports on a maintenance station or other device configured toevacuate debris from the bin 50. In other implementations, theevacuation port 80 is installed along an edge of the outer shell 6, on atop most portion of the outer shell 6, on the bottom of the robot body31, or other similar placements where the evacuation port 80 has readyaccess to the contents of the cleaning bin 50.

FIG. 2 is a block diagram of systems included within the robot 11. Therobot 11 includes a microprocessor 245 capable of executing routines andgenerating and sending control signals to actuators within the robot 11.Connected to the microprocessor 245 is memory 225 for storing routinesand sensor input and output, a power assembly 220 (e.g., a batteryand/or a plurality of amplifiers able to generate and distribute powerto the microprocessor 245), and other components included within therobot 11. A data module 240 is connected to the microprocessor 245 whichmay include ROM, RAM, an EEPROM or Flash memory. The data module 240 maystore values generated within the robot 11 or to upload new softwareroutines or values to the robot 11.

The microprocessor 245 is connected to a plurality of assemblies andsystems, one of which is the communication system 205 including anRS-232 transceiver, radio, Ethernet, and wireless communicators. Thedrive assembly 210 is connected to the microprocessor 245 and includesright and left differentially driven wheels 45, right and left wheelmotors, and wheel encoders. The drive assembly 210 is operable toreceive commands from the microprocessor 245 and generate sensor datatransmitted back to the microprocessor 245 via the communication system205. A separate caster wheel assembly 230 is connected to themicroprocessor 245 and includes a caster wheel 35 and a wheel encoder.The cleaning assembly 215 is connected to the microprocessor 245 andincludes a primary brush 65, a secondary brush 60, a side brush 20, andbrush motors associated with each brush. Also connected to themicroprocessor is the sensor assembly 235 which may include infraredproximity sensors 75, an omnidirectional detector 15, mechanicalswitches installed in the bumper 5, wheel-floor proximity sensors 70,stasis sensors, a gyroscope 71, and infrared cliff sensors 30.

Referring to FIGS. 3A-3E, example locations of the cleaning bin 50 and afilter 54 disposed on the chassis 31 and the outer shell 6 are shown.FIG. 3A displays a robot 300A with an evacuation port 305 disposed onthe top of the robot 300A, and more specifically installed on the top ofa cleaning bin 310A. The cleaning bin 310A may or may not be removablefrom the chassis 31 and outer shell 6, and if removable, is removablesuch that the bin 310A separates from (e.g., is releasably engageablewith) a back portion 312A of the robot 300A.

Referring to FIG. 3B, a cleaning bin 310B is installed towards the rearportion of a robot 300B and includes a latch 315. In someimplementations, a portion of the cleaning bin 310B slides toward theforward portion of the robot 310B when the latch 315 is manipulated,providing access to the contents of the cleaning bin 310B for removal.Additionally or alternatively, the cleaning bin 310B is removable from aback portion 312B of the robot 310B to provide access to the contents ofthe cleaning bin 310B for removal and/or to provide access to a filter(e.g., filter 54) disposed substantially within the cleaning bin 310B.In this implementation, the cleaning bin latch 315 may be manipulatedmanually by the operator or autonomously by a robotically drivenmanipulator.

Referring to FIG. 3C, a robot 300C including a cleaning bin 310C locatedon a rearmost side wall 320 of the outer shell 6. The cleaning bin 310Chas a set of movable doors 350, each slidable along the side of therobot body 31 and each recessable under the outer shell 6. In someimplementations, with the doors 350 recessed under the outer shell 6,the cleaning bin 310C is configured to accept and mate with an externalevacuation port.

FIG. 3D provides a bottom view of a robot 300D and the bottom of thecleaning bin 310D located on the bottom, rear portion of the robot 300D.The cleaning bin 310D has a latch 370 allowing a door 365 located on thebottom of cleaning bin 310D to slide towards the forward portion of therobot 300D so that contents of the cleaning bin 310D may be removed. Incertain implementations, the cleaning bin 310D supports a filter (e.g.,filter 54 shown in FIG. 1C) and the cleaning bin 310D is removable froma back portion 312D of the robot 300D to facilitate cleaning and/orreplacing the filter. The cleaning bin 310D and latch 370 may bemanipulated manually by an operator or autonomously by a roboticallydriven manipulator.

FIG. 3E provides a bottom view of a robot 300E and the floor of thecleaning bin 310E located on the bottom, rear portion of the robot 300E.The cleaning bin 310E includes a port 380 for accessing contents of thecleaning bin 310E. An evacuation hose may be attached to the port 380 toevacuate the cleaning bin 310E. In certain implementations, the cleaningbin 310E is removable from a back portion 312E of the robot 300D toaccess and clean a filter disposed within the cleaning bin 310 (e.g.,filter 54 shown in FIG. 1C).

Referring to FIG. 3F, a robot 300F includes a cleaning bin 310F disposedalong a rear robot portion 312F. In some implementations, the cleaningbin 310F includes at least one evacuation port 380 on a rear side (threeare shown). The evacuation ports 380 may be configured to receive anevacuation hose for removing debris from the bin 310F. Additionally oralternatively, the evacuation ports 380 may be configured to facilitatemanual removal of debris (e.g., by holding the bin 310F to allow debriswithin the bin to fall out of the bin under the force of gravity).

Referring to FIG. 3G, a robot 300G includes a cleaning bin 310G locatedon a rear robot portion 312G. The cleaning bin 310G includes one or moreevacuation ports 380 on a side portion (e.g. left and/or right sides).The evacuation ports 380 are configured to receive an evacuation hosefor removing debris from the bin 310G.

The robotic cleaner 11 may receive a number of different cleaning bins50. For example, referring to FIG. 4A, a cleaning bin 400A is configuredto mate with external vacuum evacuation ports. The vacuum bin 400Adefines a main chamber 405A having a sloped floor 410A that aidsmovement of debris towards evacuation ports 415, 420, 425. A first sideevacuation port 415 is located adjacent a center evacuation port 420which is located between the first side evacuation port 415 and a secondside evacuation port 425. Located on the side walls of the bin 400A aretwo evacuation outlets 430 that are installed to further aid a vacuum inits evacuation operation.

Referring to FIG. 4B, a bin 400B includes teeth 450 along a mouth edge452 of the bin 400B. The teeth 450 reduce the amount of filament buildup on the main brush 60 and/or the secondary brush 65 (see FIG. 1B) byplacing the bin 400B close enough to the brush 60, 65 such that theteeth 492 slide under filament build up on the brush 60, 65 and pull offfilament build up as the brush 60, 65 rotates. In some examples, the bin400B includes between about 24-36 teeth. In the example shown, the bin400B defines a sweeper bin portion 460 and a vacuum bin portion 465. Thecomb or teeth 450 are positioned between the sweeper bin portion 460 andthe vacuum bin portion 465 and arranged to lightly comb the sweeperbrush 60 as the sweeper brush 60 rotates. The comb or teeth 450 removeerrant filaments from the sweeper brush 60 that accumulate either on theteeth 450 or in the sweeper bin portion 460. The vacuum bin portion 465and the teeth 450 above it do not interfere with each other. The bin400B carries a vacuum assembly 480 (e.g. a vacuum motor/fan) configuredto draw debris through a channel such as the channel defined a pair ofsqueegees 470A and 470B in the vacuum bin portion 460.

The bin 400B includes electrical contacts 482A, 482B, which arereleasably engageable with corresponding electrical contacts on therobot body 31 such that power is supplied to the bin 400B when the bin400B is engaged with the robot body 31. In some implementations, thepower is provided to the vacuum assembly 480. In certainimplementations, the electrical contacts 482A, 482B can providecommunication to a bin microprocessor 217. The filter 54 (shown in FIG.1C) can separate the vacuum bin portion 460 from the vacuum assembly480. In some examples, the filter 54 pivots open along a side, top, orbottom edge for servicing. In other examples, the filter 54 slides outof the vacuum bin portion 460.

In some instances, the bin 50 includes a bin-full detection system forsensing an amount of debris present in the bin 50. For example,referring to FIGS. 5A-5B, the bin-full detection system includes anemitter 755 and a detector 760 housed in the bin 50. A housing 757surrounds each of the emitter 755 and the detector 760 and issubstantially free from debris when the bin 50 is also free of debris.In one implementation, the bin 50 is detachably connected to the roboticcleaner 11 and includes a brush assembly 770 for removing debris andsoot from the surface of the emitter/detector housing 757. The brushassembly 770 includes a brush 772 mounted on the robot body 31 andconfigured to sweep against the emitter/detector housing 757 when thebin 50 is removed from or attached to the robot 11. The brush 772includes a cleaning head 774 (e.g. bristles or sponge) at a distal endfarthest from the robot 11 and a window section 776 positioned toward abase of the brush 772 and aligned with the emitter 755 or detector 760when the bin 50 is attached to the robot 11. The emitter 755 transmitsand the detector 760 receives light through the window 776. In additionto brushing debris away from the emitter 755 and detector 760, thecleaning head 774 reduces the amount of debris or dust reaching theemitter 755 and detector 760 when the bin 50 is attached to the robot11. In some examples, the window 776 comprises a transparent ortranslucent material and is formed integrally with the cleaning head774. In some examples, the emitter 755 and the detector 760 are mountedon the chassis 31 of the robot 11 and the cleaning head 774 and/orwindow 776 are mounted on the bin 50.

Referring to FIG. 6A, in some implementations a sweeper robot 11includes a brush 60 and a flap 65 that sweep or otherwise agitate debrisfrom the cleaning surface for movement into a bin 700A having an emitter755 and a detector 760, each positioned near a bin mouth 701 (e.g., anopening defined by the bin 700A).

Referring to FIG. 6B, in certain implementations a bin 700B includes avacuum/blower motor 780, and an emitter 755 and a detector 760 locatednear an inlet 782 of a vacuum flow path into the bin 700B. The robotbody 31 of the robot 11 includes a robot vacuum outlet 784 that engages(e.g., fits flush with) the vacuum inlet 782 of the bin 700B. By placingthe emitter 755 and the detector 760 near the debris inlet 782, debriscan be detected along the intake flow path rather than within the debrischamber 785. Therefore, a bin-full condition may be triggered wheneither the amount of debris swept or vacuumed along the flow path isextremely high (which may typically be a rare scenario), or when thedebris chamber 785 is full (e.g. debris is no longer deposited therein,but instead backs up along the intake flow path near the inlet 782).

Referring to FIG. 6C, in some implementations, a combined vacuum/sweeperbin 700C includes an emitter 755 and a detector 760 pair positioned neara sweeper bin inlet 782A and a vacuum bin inlet 782B. The emitter 755and detector 760 mounted near the sweeper bin inlet 782A are supportedon the robot body 31 of the robot 11. Additionally or alternatively, theinlet sensors 755, 760, several emitter arrays 788 are positioned on aninterior surface of the bin 700C (e.g., a bottom interior surface of thebin 700C) and one more detectors 760 are positioned on a substantiallyopposite interior surface of the bin 700C (e.g., a top interior surfaceof the bin 700C). As described in further detail below, signals from thedetectors 760 located along the intake flow path, as well as thecontainer of the bin 700C, may be compared for detecting the presence ofdebris and/or for determining bin fullness. For example, when a heavyvolume of debris is pulled into the bin 700C by the brush 60, flapper65, and/or vacuum motor 780, the detectors 760 located along the flowpath may generate a low detection signal. However, detectors 760 locatedon the top interior surface of the bin 700D will not detect a full bin700C, if it is not yet full. Comparison of the detector signals avoids afalse bin-full condition.

FIGS. 7A-7E illustrate a transmissive optical debris-sensing system fordetecting debris within the bin 50. As shown in FIG. 7A, in someexamples, the bin 50 includes emitters 755 located on a bottom interiorsurface 51 of the bin 50 and detectors 760 located on an upper interiorsurface 52 of the bin 50. The emitters 755 emit light that traverses theinterior of the bin 50 and which may be detected by the detectors 760.When the interior of the bin 50 is clear of debris, the transmittedlight from the emitters 755 produces a relatively high signal strengthin the detectors 760, because very little of the transmitted light isdiverted or deflected away from the detectors 760 as the transmittedlight passes through the empty interior of the bin 50. By contrast, whenthe interior of the bin 50 contains debris, at least some of the lighttransmitted from the emitters 755 is absorbed, reflected, or diverted asthe light strikes the debris, such that a lower proportion of theemitted light reaches the detectors 760. The degree of diversion ordeflection caused by the debris in the interior of the bin 50 correlatespositively with the amount of debris within the bin 50.

By comparing the signals generated by the detectors 760 when the bin 50does not contain debris to subsequent signal readings obtained by thedetectors 760 as the robot 11 sweeps and vacuums debris into the bin 50during a cleaning cycle, the presence of debris within the bin 50 may bedetermined. For example, when the subsequently polled detector signalsare compared to initial detector signals (e.g., signals taken when thebin 50 is substantially empty), a determination can be made whether thedebris accumulated within the bin 50 has reached a level sufficient totrigger a bin-full condition.

One example bin configuration includes one emitter 755 and two detectors760. Another configuration includes positioning one or more emitters 755and detectors 760 in the bin 51 and cross-directed in mutuallyorthogonal directions. The robot 11 may determine that heavy debris hasaccumulated on the bottom of the bin 50 but has not filled the bin 50,when signals generated by a first detector 760 on the inner top surface52 is relatively low and signals generated by a second detector 760 onan inner side wall (which detects horizontally-transmitted light) doesnot meet a bin-full threshold. Additionally or alternatively, when bothdetectors 760 report a relatively low received-light signal, it may bedetermined that the bin 50 is full.

Referring to FIG. 7B, in some implementations, the bin 50 includes adetector 760 proximate a calibration emitter 805, both disposed behind ashield 801 on the top interior surface 52 of the bin 50. An emitter 755is disposed on the bottom interior surface 51 of the bin 50. Acalibration signal reading is obtained by emitting light from thecalibration emitter 805 which is then detected by the detector 760 as afirst reading. The translucent or transparent shield 801 preventsemission interfere between the transmission of light from thecalibration emitter 805 to the detector 760 with dust or debris from thebin 50. The emitter 755 then transmits light across the interior of thebin 50 and the detector 760 takes a second reading of received light. Bycomparing the second reading to the first reading, a determination maybe made whether the bin 50 is full of debris. In some examples, therobot 11 includes sensors 755, 760 positioned along a debris flow pathprior to a mouth 53 of the bin 50. The bin full sensors 755, 760 maydetect debris tending to escape from the bin 50.

Referring to FIG. 7C, in some implementations, the bin 50 includes twoemitter arrays 788 and two detectors 760. Each emitter array 788 mayinclude several light sources. The light sources may each emit lightfrequencies that differ from one another within the same emitter arrays788. For example, varying frequencies of light emitted by the lightsources exhibit various levels of absorption by debris of differentsizes. A first sub-emitter within the emitter array 788 may emit lightat a first frequency, which is absorbed by debris of very small particlesize, while a second sub-emitter within the emitter arrays 788 may emitlight at a second frequency which is not absorbed by small-sized debrisparticles. The robot 11 may determine whether the bin 50 is full evenwhen the particle size of the debris varies by measuring and comparingthe received light signals from the first and second sub-emitters.Undesirable interference with the optical transmissive detection systemmay be avoided by employing sub-emitters emitting light at differentfrequencies.

Multiple emitter arrays 788 and detectors 760 may provide more accurateand reliable bin fullness detection as compared to, for example, asingle emitter and detector pair. In the example shown, the multipleemitter arrays 788 provide cross-bin signals to detect potential binblockages. One possible blockage location is near an intruding vacuumholding bulkhead 59, which partially divides the bin 50 into two lateralcompartments. Additionally or alternatively, a blockage may occur whenreceived debris of a large enough size (e.g. paper or hairball) blocksand compartmentalizes the bin 50 at least temporarily. In certainimplementations, a blockage occurs when shifting, clumping, moving,vibrated, or pushed debris within the bin creates one or morecompartments in the bin 50 (e.g., via systematic patterns ofaccumulation). If debris accumulates in one lateral compartment, but notanother, a single detector pair may not detect such accumulation. Asingle detector pair may also provide a false-positive signal from alarge debris item or clump (e.g., indicating that the bin 50 is fullwhen it is not). Multiple emitter arrays 788 located on the bottominterior surface 51 of the bin 50 and multiple detectors 760 located onthe top interior surface 52 of the bin 50 in two different lateral orfront-to-back locations covers more potential volume of the bin 50 formore accurate and reliable bin fullness detection as compared to asingle detector pair in the same or similar orientation. A histogram oraveraging of the bin detector signals or using XOR or AND on the resultsof more than one break-beam may be used to get more true positives (evendepending on the time since accumulation began).

Referring to FIG. 7D, in certain implementations, the bin 50 includes atransmissive optical detection system including two emitter arrays 788,each having a diffuser 790 diffusing emitted infrared light. The diffuselight transmitted to the interior of the bin 50 provides a steadierdetection signal generated by the detectors 760 relative to a detectionsignal generated from a concentrated beam of light from a non-diffuselight source at least because the diffuse light provides a type ofphysical averaging of the emitted signal. The detectors 760 receivingdiffused infrared light signals can measure an overall blockage amountversus interruption of only a line-of-sight break beam from one emitter.

Referring to FIG. 7E, in certain implementations, the bin 50 includes alight pipe or fiber-optic pathway 792 disposed on the bottom interiorsurface 51 of the bin 50. Light from a light source 793 in the bin 50travels along the fiber-optic pathway 792 and is emitted fromdistributor terminals 794. This bin configuration centralizes lightproduction to the single light source 793, rather than supplying powerto several independent light sources, while distributing light acrossthe bin 50. The distributor terminals 794 may also include a diffuser790, as discussed above with respect to FIG. 7D.

Referring to FIGS. 7F-7H, in some implementations, the bin 50 includesoptical debris detection by reflective light transmission. In oneexample, as shown in FIG. 7F, the bin 50 includes a shielded emitter 756located near a detector 760. Light emitted by the shielded emitter 756does not travel directly to the detector 760 because of the shielding.However, light emitted from the emitter 756 is reflected by the interiorsurface 55 of the bin 50, and traverses an indirect path to thedetectors 760. The attenuation of the reflected light caused by debriswithin the bin 50 may be comparatively greater than in a directtransmissive configuration, because the path the reflected light musttravel within the bin 50 is effectively doubled, for example. Althoughthe shielded emitter 756 and detector 760 are illustrated as beingproximate to each other, they may be additionally or alternativelyspaced apart from each other. The emitter 756 and detector 760 may bepositioned on the same surface, or on different surfaces.

Referring to FIG. 7G, in certain implementations, two sets of shieldedemitters 756 and detectors 760, each located on opposite horizontalsides of the interior of the bin 50. In this configuration, lightreceived by each detector 760 may be a combination of light directlytransmitted from the shielded emitter 756 located on the opposite sideof the bin 50, as well as light reflected off the interior surface 55 bythe proximal shielded emitter 756. In some examples, a first set ofshielded emitters 756 and detectors 760 is located on a bin surfaceadjacent to a second set of shielded emitters 756 and detectors 760. Inone example, a single shielded emitter 756 and detector 760 pair islocated on a bottom surface 51 of the bin 50.

FIG. 7H illustrates a configuration in which the bin 50 includes adiffusive screen 412 placed along the transmission path of the shieldedemitter 756 disposed on a bottom surface 51 of the bin 50. The diffusivescreen 790 diffuses light emitted from the shielded emitter 756 thatreflects off various surfaces of the interior 55 of the bin 50 beforereaching the detector 760, thereby providing a detection signal thatreflects a broad area of the interior of the bin 50.

Referring to FIGS. 8A-8E, in some implementations, the bin 50 includesan optical detection system 800 that detects debris moving through acombination of reflective and transmissive signals in the bin 50. Theoptical detection system 800 includes a first receiver 802A, a secondreceiver 802B, a first emitter array 804A, and a second emitter array804B. During use, debris 48 enters the bin 50 through the mouth 53 andforms an accumulation 49 extending from the bottom surface 51 of thebin. As debris 48 continues to enter the bin 50, the accumulation 49 canincrease in size in a direction defined from the bottom surface 51 tothe top interior surface 52 (compare FIGS. 8A, 8B, and 8C). As describedin further detail below, the emitter arrays 804A,B are sequentiallyenabled and disabled (e.g., pulsed at a substantially constantfrequency) while the receivers 802A,B are synchronously sampled tomeasure reflected and transmissive signals and further processed todetect the debris 48 moving past the optical detection system 800 and todetermine whether the bin 50 is full of debris (e.g., whetheraccumulation 49 of the debris 48 has size and/or density characteristicsindicative of a “bin full” condition).

When the bin 50 is empty (as shown in FIG. 8A) or contain anaccumulation 49 of debris below the receivers 802A,B and emitters 804A,B(as shown in FIG. 8B), the transmissive signal received at each receiver802A,B is greater than (e.g., substantially greater than) the reflectedsignal received at the respective receiver. As the bin 50 fills withdebris 48 (e.g., during operation), the magnitude of the reflectedsignal can increase relative to the magnitude of the transmissive signalmeasured by each respective receiver 802A,B. When the accumulation 49 ofdebris has filled the bin 50 (as shown, for example, in FIG. 8C), thereflective signal is about equal to or greater than the transmissivesignal measured at the respective receiver 802A,B. As discussed infurther detail below, a comparison of the reflected signal measured atthe receiver 802A with the reflected signal measured at the receiver802B can provide an indication of whether the accumulation 49 of debrisin the bin 50 is symmetrical (FIG. 8C) or axisymmetrical (FIGS. 8D and8E).

The first and second receivers 802A,B are disposed on substantiallyopposite sides of the mouth 53 of the bin and separated from one anotheralong the largest dimension of the mouth 53. The first and secondreceivers 802A,B are generally directed toward one another such thateach receiver may measure light originating from a source proximate tothe other receiver, as described in further detail below. In someimplementations, the first and second receivers 802A,B are supported onsubstantially opposing side walls 57 of the bin 50. The mouth 53 can bean opening in a substantially vertical plane perpendicular to thecleaning surface when the bin 50 is mounted on the robot body 31. Forexample, the mouth 53 can be a substantially rectangular opening, withthe side walls 57 define the short sides of the substantiallyrectangular opening and the bottom surface 51 and the top portion 52define the long sides of the substantially rectangular opening.

In some implementations, the first and second receivers 802A,B supportedon substantially opposing side walls 57 of the bin 50 can reduce thelikelihood of false positive signals by providing redundant measurementsthat may be compared to one another to determine a bin-full condition oran anomaly in debris accumulation in the bin. For example, if thereflected signals received by the first and second receivers 802A,B aresubstantially similar, this can be an indication that the bin is full.Additionally or alternatively, if the reflected signal received by thefirst receiver 802A is larger (e.g., substantially larger) than thereflected signal received by the second receiver 802B, this can be anindication of axisymmetric debris accumulation in the portion of the binclosest to the first receiver 802A (as shown, for example, in FIG. 8D).Similarly, if the reflected signal received by the second receiver 802Bis larger (e.g., substantially larger) than the reflected signalreceived by the first receiver 802A, this can be an indication ofaxisymmetric debris accumulation in the portion of the bin closest tothe second receiver 802B (as shown, for example, in FIG. 8E). In certainimplementations, the redundant measurements afforded by the first andsecond receivers 802A,B can detect an anomaly such as a piece of paperor other obstruction in the area of a respective one of the first andsecond receivers 802A,B.

The first and second receivers 802A,B and the first and second emitterarrays 804A,B are disposed toward the top interior surface 52 of the bin50 to bias the sensing area toward the top of the bin 50, where most ofthe debris enters the bin 50 in certain implementations. Additionally oralternatively, positioning the first and second receivers 802A,B and thefirst and second emitter arrays 804A,B toward the top interior surface52 of the bin 50 facilitates bin-full detection (e.g., reduces thelikelihood of false positive signals) in implementations in which thebin 50 fills from the bottom surface 51 to the top surface 52. Incertain implementations, positioning the receivers 802A,B and emitterarrays 804A,B toward the top interior surface 52 can reducedeterioration of the receivers 802A,B and emitter arrays 804A,Bresulting from the accumulation of debris on the receivers 802A,B atleast because the top portion of the bin 50 is typically the position ofleast debris accumulation.

The first and second emitter arrays 804A,B are disposed proximate to andbelow the respective first and second receivers 802A,B such that eachemitter array 804A,B emits a signal substantially diagonally across atleast a portion of the mouth 53. Each emitter array 804A,B is orientedto emit a signal across the mouth 53 of the bin 50, toward a respectiveopposing receiver 802A,B. For example, the first emitter array 804Aemits a signal toward the second receiver 802B such that the secondreceiver 802B receives a transmissive (e.g., unreflected) portion of asignal from the first emitter array 804A and the first receiver 802Areceives a reflected portion of a signal from the first emitter array804A when there is no debris in the bin 50. The second emitter array804B and the first receiver 802A are arranged relative to one another inan analogous manner.

Each emitter array 804A,B is substantially unshielded and may includeone or more light sources 806 (e.g., two light sources). Inimplementations in which the emitter arrays 804A,B include more than onelight source 806, light sources 806 of each array are arranged one abovethe other and spaced apart from one another. In these implementations,such spacing of multiple light sources 806 can facilitate emission ofsignals that cover all or a substantial portion of the mouth 53 withoutrequiring custom lensing of the light sources 806. The light sources 806may be arranged to emit signals substantially covering the mouth 53(e.g., covering more than about 50% of the area of the mouth 53) whenall of the light sources 806 emit a signal. In certain implementations,the first receiver 802A and the first emitter array 804B issubstantially identically arranged as the second receiver 802A and thesecond emitter array 804B such that, for example, the signals emitted bythe first emitter array 804 intersect (e.g., criss-cross) the signalsemitted by the second emitter array 804 along an axis substantiallybisecting the mouth 53.

In some implementations, the receivers 802A,B and the emitter arrays804A,B are supported on the robot body 31, just upstream of the mouth 53of the bin 50 such that the receivers 802A,B and the emitter arrays804A,B remain disposed on the robot body 31 when the bin 50 isdisengaged from the robot body 11. In some implementations, at leastsome of the receivers 802A,B and the emitter arrays 804A,B aremechanically coupled to the bin 50 and, thus, move with the bin 50 whenthe bin 50 is disengaged from the robot body 11. The receivers 802A,Band the emitter arrays 804A,B may be in wireless communication with themicroprocessor 245 and/or the bin microprocessor 217 (see FIG. 2). Thewireless communication between the microprocessor 245 and/or binmicroprocessor 217 and the optical detection system 800 can include oneor more of the following: infrared communication, electromagneticcommunication, and radiofrequency communication.

Referring to FIG. 9A, the optical detection system 800 includes a debrismonitoring routine 900 to monitor passage of debris into the bin. Thedebris monitoring routine 900 may be implemented through communicationbetween the optical detection system 800 and one or more of the binmicroprocessor 217 and the microprocessor 245.

The first emitter array 804A and the second emitter array 804B areactivated and deactivated 902 to emit respective signals across themouth 53 of the bin 51. The activation and deactivation 902 is donesequentially such that the first emitter array 804A and the secondemitter array 804B are each deactivated during a first time step, thefirst emitter array 804A is activated and the second emitter array 804Bis deactivated during a second time step, and the first emitter array804A is deactivated and the second emitter array 804B is activatedduring a third time step. In some implementations, the activation anddeactivation 902 of the first and second emitter arrays 804A,B is cycledat a substantially constant frequency of about 0.5 kHz to about 20 kHz(e.g., about 1 kHz).

The first receiver 802A is measured 904. The measurement can be taken ata substantially constant rate of about 0.25 kHz to about 10 kHz (e.g.,about 4 kHz). In some implementations, the second receiver 802B ismeasured in an analogous manner. The measured signals from the firstreceiver 802A and the second receiver 802B can reduce the likelihood offalse positive measurements by, for example, comparing the measuredsignals from the first receiver 802A and the second receiver 802B.Additionally or alternatively, the measured signals from the firstreceiver 802A and the second receiver 802B can be used to determinewhether the debris is entering the bin 50 from the right side or fromthe left side.

The movement of debris through the mouth 53 is detected 906 based atleast in part on a first measurement obtained when the first and secondemitter arrays 804A,B are each deactivated, a second measurementobtained when the first emitter array 804A is activated and the secondemitter array 804B is deactivated, and a third measurement obtained whenthe first emitter array 804A is deactivated and the second emitter array804B is activated. For example, detecting 906 the movement of debristhrough the mouth 53 can include comparing an instantaneous value of ameasurement to its respective average value. The impact of ambient lightcan be filtered out by adjusting the magnitudes of second and thirdmeasurements based at least in part on the first measurement, taken withboth emitter arrays 804A,B deactivated. Additionally or alternatively,as described in further detail below, a base brightness can bedetermined through a dynamic calibration routine initiated, for example,based at least in part upon detection of an initiation condition.

In some implementations, the first, second, and third measurements areprocessed as a function of time and changes in at least one of theprocessed measurements (e.g., at least one of the processed second andthird measurements) are detected. For example, processing as a functionof time may include a low pass filter to baseline the measured value toan average value. Such low pass filtering can reduce sensor-to-sensorvariation and, thus, for example, improve the robustness of the debrisdetection using the optical debris detection system 800.

The detected 906 debris through the mouth 53 of the bin 51 can includegenerating a signal to initiate a spot coverage routine to move therobot 11 over an area corresponding to the detected debris, as describedin detail below. In certain implementations, the initiation of such aspot coverage routine is based at least in part on a quantified amountof debris. For example, the spot coverage routine can be initiatedand/or adjusted if a large amount of debris is detected in a given area.

For the sake of clarity of description, the debris monitoring routine900 has been described as monitoring passage of debris into a debris binbased on measuring signals at the first receiver 802A. However, itshould be noted that the debris monitoring routine 900 can additionallyor alternatively include analogous measurements of signals at the secondreceiver 802B.

In some implementations, referring to FIG. 9B, the optical detectionsystem 800 includes a debris quantifying routine 975. The debrisquantifying routine 975 may be implemented through communication betweenthe optical detection system 800 and one or more of the binmicroprocessor 217 and the microprocessor 245.

The debris quantifying routine 975 includes periodically assigning 978 ascore to the debris passing through the mouth 53. The score can bebased, at least in part, on the amount of light determined to be blockedby the debris, which can be substantially quantified based on one ormore of the following: the magnitude of the measured debris signal(indicative of the size of the debris) and the duration of the measureddebris signal (indicative of the concentration of debris). The assigneddebris score is added 980 to previous debris scores. The adding 980 ofthe present debris score to the previous debris scores can includeregularly decrementing 988 the running sum of the debris scores by afixed amount. Such regular decrementation is sometimes referred to as“leaky” integration and can reduce the likelihood that small and lightdebris (e.g., loose carpet fibers or other “ambient” debris that is partof the surface being cleaned) will be detected as debris while stillallowing large pieces of debris and high concentrations of small debristo be detected. The amount of decrementation can be a fixed value.Additionally or alternatively, the amount of decrementation can beadjusted (e.g., manually adjusted) based on the surface being cleanedsuch that surfaces that shed (e.g., carpet) will have a generally higherdecrement than surfaces that do not shed (e.g., hardwood floors).

If the summed debris score is greater than a threshold 982, a dirtdetection signal is generated 984 and the summed debris score is reset986 (e.g., reset to zero). If the summed debris score is not greaterthan the threshold 982, periodic debris scores will continue to beassigned 978 and added 980 to previous debris scores. The threshold fordetermining the generation of the debris signal can be a fixed valuestored in the bin microprocessor 217. In certain implementations, thethreshold can be lower at the beginning of the cleaning cycle (e.g.,when the detected debris signal is more likely to be indicative ofdebris on the floor) than at the end of the cleaning cycle. Additionallyor alternatively, the threshold can increase the more often debris isdetected. This can reduce the likelihood that the robot 11 will run aspot coverage pattern too many times.

Referring to FIG. 9C, in some implementations, the optical detectionsystem 800 includes a bin-full detection routine 990 to determinewhether the bin 50 is full of debris. The bin-full detection routine 990may be implemented through communication between the optical detectionsystem 800 and one or more of the bin microprocessor 217 and themicroprocessor 245.

The first emitter array 804A and the second emitter array 804B areactivated and deactivated 992 to emit respective signals across themouth 53 of the bin 51, and the first receiver 802A is measured 994. Theactivation and deactivation 992 and the measurement 994 is analogous tothe activation and deactivation and measurement described above withrespect to the debris monitoring routine 900 such that, in someimplementations, the same set of measurements is used as part of thedebris monitoring routine 900 and the bin-full detection routine 990.

The amount of debris in the bin is determined 996 based at least in parton comparing a first reflective signal to a first transmissive signal,where the reflective signal is derived from a measurement by the firstreceiver 802A when the first emitter array 804A is activated and thesecond emitter array 804B is deactivated and the transmissive signal isderived from a measurement by the first receiver 802A when the firstemitter array 804A is deactivated and the second emitter array 804B isactivated.

For the sake of clarity of description, the bin-full detection routine990 has been described as determining whether the bin is full based onmeasuring signals at the first receiver 802A. However, it should benoted that the debris monitoring routine 900 can additionally oralternatively include analogous measurements of signals at the secondreceiver 802B.

Referring to FIG. 9D, determining 996 whether the bin 50 is full ofdebris may include a threshold setting routine 1050. The thresholdsetting routine 105 may be implemented through communication between theoptical detection system 800 and one or more of the bin microprocessor217 and the microprocessor 245.

The threshold setting routine 1050 includes comparing 1052 a measuredreflective signal to a measured transmissive signal (e.g., thereflective and transmissive signals measured by the first receiver 802Aand/or the second receiver 802B). In some implementations, thecomparison 1052 of the measured reflective signal to the measuredtransmissive signal is based on an average (e.g., time-averaged) valueof each signal. Such averaging can reduce the likelihood of falsepositive bin-full results by, for example, reducing the impact ofspurious and/or transient conditions on bin-full detection. In certainimplementations, the measured reflective signal and the measuredtransmissive signal are compared 1052 at a rate of 1 Hz to 100 Hz (e.g.,about 60 Hz).

If the measured reflective signal is less than the measured transmissivesignal 1054, the threshold setting routine 1050 continues to compare themeasured reflective signal to the measured transmissive signal. Such acondition represents a bin that is relatively empty since light emittedby an emitter array (e.g., emitter arrays 804A,B) generally reaches areceiver (e.g., receivers 802A,B) disposed across the mouth 53 of thebin. If the measured reflective signal is greater than or equal to themeasured transmissive signal 1054, the reflective signal is compared tothe transmissive signal to determine 1066 whether both signals are lessthan a minimum target value (e.g., equal to zero or about equal tozero). This reflects an anomalous condition, such as extremely rapidfilling of the bin. If both signals are equal to zero, a bin-full signalis generated 1062.

The value at which the reflective signal becomes greater than or equalto the transmissive signal is referred to as the crossover value andgenerally represents an indication that the bin is becoming full sincelight emitted by an emitter array is transmitted and scattered inapproximately equal amounts as it is directed across the mouth 53 of thebin. In general, setting the threshold value as a function of thecrossover value of the receiver can serve to self-calibrate the bin-fulldetection.

In some implementations, setting 1056 the threshold includes multiplyingthe crossover value by a fixed multiple (e.g., doubling the crossovervalue). In certain implementations, setting 1056 the threshold includesmultiplying the crossover value by a value proportional (e.g., directlyproportional, inversely proportional) to the value of the crossoverpoint. Additionally or alternatively, setting 1056 the threshold caninclude multiplying the crossover value by a value proportional (e.g.,directly proportional, inversely proportional) to the amount of time inwhich the crossover point was reached and/or to the peak transmissivesignal.

The set threshold value can be reduced 1058 in a regular decrement overtime. This can ensure that a bin-full condition will eventually bereached and, thus, reduces the likelihood that the robot 11 willcontinue to attempt to clean in the event of an error or an anomalouscondition.

The reflective signal is compared 1060 to the set threshold. Given thatthe bin-filling process is generally slow, this comparison can be doneat a relatively frequency of about 1 Hz to about 100 Hz (e.g., about 60Hz).

If the reflective signal is greater than or equal to the set threshold,a bin-full signal is generated 1062. In some implementations, thethreshold value is set as an average of the signals measured by thefirst and second receivers 802A,B. Additionally or alternatively, thegeneration 1062 of a bin full signal can be based at least upon acomparison of the threshold to an average of the reflected signalsmeasured by the first and second receivers 802A,B. As described infurther detail below, this bin-full signal can be used to alert the userto the bin-full condition. In certain implementations, the bin-fullsignal is used to initiate a navigation routine to find a dockingstation (e.g., maintenance station 1250). Additionally or alternatively,the generation 1062 of the bin-full signal can disable at least aportion of the cleaning head 40 such that additional debris is not drawninto the bin 50.

The reflective signal continues to be compared to the transmissivesignal to determine 1064 whether the reflective signal has become lessthan or equal to the transmissive signal after having been greater thanthe transmissive signal (this is sometimes referred to as becoming“uncrossed”). If the reflective signal is greater than or equal to thetransmissive signal and the threshold value is set, the threshold valuecontinues to be reduced 1058 until the reflective signal is greater thanor equal to the threshold. If the reflective signal becomes less thanthe transmissive signal after the threshold value has been set, thethreshold value is reset 1067 (e.g., set to a large value and/orresetting a flag) and the reflective signal continues to be compared tothe transmissive signal 1054 to determine 1054 a new crossover point andset 1056 a new threshold. Such dynamic resetting of the thresholdreduces the likelihood of false-positive bin full detection resultingfrom, for example, debris becomes lodged and then dislodged in thedebris bin 50.

Although the optical detection system 800 has been described as beingimplemented in an autonomous, robot cleaning device, the opticaldetection system 800 can be additionally or alternatively incorporatedinto a non-autonomous cleaning device (e.g. a conventional vacuumcleaner).

The debris signal from a debris detection system (e.g., an opticaldetection system such as the optical detection system 800 or apiezoelectric debris detection system) can be used to alter operation ofthe robot 11, including selecting a behavioral mode (such as enteringinto a spot cleaning mode), changing an operational condition (such asspeed, power or other), steering in the direction of debris(particularly when spaced-apart left and right debris sensors are usedto create a differential signal), or taking other actions. For example,based at least on a detected debris signal, the robot 11 cansubstantially immediately begin movement through a spot coveragepattern, including the spot coverage patterns described in furtherdetail below. The microprocessor 25 can move the robot 11 through one ormore of the spot coverage patterns below by controlling the driveassembly 210 based at least in part on a signal received from thegyroscope 71. For example, the signal received from the gyroscope 71 canallow the robot 11 to move in a direction relative to the sensed debrisand/or to return to the position of the sensed debris.

Referring to FIG. 9E, in some implementations, the optical detectionsystem 800 includes a dynamic calibration routine 1100 to set 1116 basebrightness used for debris detection (e.g., through the debrismonitoring routine 900 shown in FIG. 9A and described above). Asindicated above, the base brightness can be subtracted from subsequentsignals received at receivers 802A,B to improve, for example, theaccuracy of debris detection. In some implementations, the calibrationroutine 1100 can activate and/or deactivate a bin-full indicator (e.g.,bin full indicator 1015 in FIG. 12A) based at least in part ondetermining whether the bin is full. The dynamic calibration routine1100 may be implemented through communication between the opticaldetection system 800 and one or more of the bin microprocessor 217 andthe microprocessor 245.

The dynamic calibration routine 1100 includes applying 1104 a firstpulse width modulation duty cycle to the first emitter array 804A if aninitiation condition is detected 1102 and measuring 1106 the signal fromthe first emitter array 804A at the second receiver 802B. If the dutycycle of the first emitter array 804A is determined 1110 to be greaterthan a limit, a second pulse width modulation duty cycle is applied 1108to the first emitter array 804A and a second signal is measured 1112 atthe second receiver 802B. If the difference between the first measuredsignal and the second measured signal is greater than a threshold, themeasured 1112 second signal is set 1116 as the base brightness. As usedherein, a pulse width modulation refers to controlling the average valueof power supplied to a load (e.g., the first emitter 804A) by turningthe power to the load on and off at a fast pace, and the duty cycledescribes the proportion of “on” time to the regular interval. Thus, ascompared to a lower pulse width modulation duty cycle, a higher pulsewidth modulation duty cycle corresponds to higher power provided to theload since the power is “on” for a longer period of time.

Detecting 1102 the initiation condition can include detecting insertionof the bin 50 into the robot body 31. Additionally or alternatively,detecting 1102 an initiation condition can include detecting applicationof power (e.g., insertion of a battery 25 into robot body 31 and/orposition of a power switch) to the autonomous robotic cleaner 11. Insome implementations, detecting 1102 the initiation condition caninclude activating a bin-full indicator based at least in part ondetecting the initiation condition. For example, upon detection 1102 ofinsertion of the bin 50 into the robot body 31 a bin full indicator canbe activated. As used herein, a bin full indicator can include a visualindicator (e.g., a light emitting diode and/or a text message on a userinterface) and/or an audible indicator (e.g., an alarm).

Applying 1104 the first pulse width modulation duty cycle to the firstemitter 804A can include applying a maximum pulse width modulation dutycycle to the first emitter 804A.

Measuring 1106 the first signal at the second receiver 802B can includemeasuring the unreflected portion of the signal from the first emitterarray 804A. For example, as described above, the first emitter array804A can be arranged to emit a signal across at least a portion of themouth 53 of the bin 50. Additionally or alternatively, measuring 1106the first signal at the second receiver 802B can included measuring areflected portion of the signal from the second emitter 804B proximateto the second receiver.

Applying 1108 the second pulse width modulation duty cycle to the firstemitter array 804A includes lowering the pulse width modulation dutycycle from the first pulse width modulation duty cycle. In someimplementations, the second pulse width modulation duty cycle is loweredby a fixed percentage from the previous pulse width modulation dutycycle. Additionally or alternatively, the second pulse width modulationduty cycle can be lowered by progressively larger percentages with eachiteration of applying 1108 the second pulse width modulation duty cycleto the first emitter 804A.

Determining 1110 whether the pulse width modulation duty cycle of thefirst emitter array 804A is greater than a limit can include comparingthe pulse width modulation duty cycle of the first emitter array 804A toa limit stored in one or more of the bin microprocessor 217 and themicroprocessor 245. For example, the limit can be less than 90 percent(e.g., less than 50 percent, less than 40 percent) of the maximum pulsewidth modulation duty cycle of the first emitter array 804A.Additionally or alternatively, the limit can be any value greater thanzero.

If the determination 1110 is that the pulse width modulation duty cycleof the first emitter array 804A is less than the limit while thedifference between the first measured signal and the second measuresignal is less than the threshold, the dynamic calibration routine 1100can end. Such termination of the dynamic calibration routine 800indicates that the measured signal at the first emitter array 804A isnot changing sufficiently with a corresponding change in the first andsecond measured signals. This insufficient change in the measured signalat the first emitter array 804 can indicate that debris was present inthe bin 50 during the initiation condition. For example, an insufficientchange in the measured signal at the first emitter array 804A canindicate that debris was present in the bin 50 when the bin 50 wasinserted in the robot body 31. Additionally or alternatively, aninsufficient change in the measured signal at the first emitter array804A can indicate that debris was present in the bin 50 when a batterywas inserted into the robot body 31 and/or when power was provided tothe optical detection system 800. Accordingly, in implementations inwhich the bin full indicator is activated based at least in part on thedetection of the initiation 1102 condition, the bin full indicator canremain activated upon termination of the dynamic calibration routine1100.

Measuring 1112 the second signal at the second receiver 802B can beanalogous to measuring 1106 the first signal at the second receiver802B.

Determining 1114 whether the difference between the first measuredsignal and the second measured signal is greater than a threshold caninclude comparing the first measured signal to the second measuredsignal after each signal has been processed. For example, each of thefirst and second measured signals can be processed through a low bandpass filter. The threshold used in the determination 1114 can be aconstant stored in one or more of the bin microprocessor 21 and themicroprocessor 245.

If the determination 1114 is that the difference between the firstmeasured signal and the second measured signal is less than or equal tothe threshold, the second pulse width modulation duty cycle is decreased1115 from the second pulse width modulation duty cycle from the previousiteration. In some implementations, the second pulse width modulationduty cycle is decreased 1115 by between about 1 percent to about 30percent (e.g., about 10 percent) in each successive iteration. Incertain implementations, the second pulse width modulation duty cycle isdecreased 1115 by progressively larger amounts in each successiveiteration.

If the determination 1114 is that the difference between the firstmeasured signal and the second measured signal is greater than thethreshold, the second measured signal is set to the base brightness(e.g., through storage in one or more of the bin microprocessor 21 andthe microprocessor 245). Additionally or alternatively, a bin-fullindicator can be deactivated based at least in part on the determination1114 that the difference between the first measured signal and thesecond measured signal is greater than the threshold. For example, thedetermination 1114 of a difference greater than the threshold can be anindication that the bin 50 is not full upon the initiation conditionand, thus, the bin-full indicator can be deactivated.

While the dynamic calibration routine 1100 is described herein as beingbased on signals emitted from the first emitter array 804A and receivedat the second receiver 802B, it should be appreciated that the dynamiccalibration routine 1100 can additionally or alternatively be based onsignals emitted from the second emitter array 804B and received at thefirst receiver 802A.

Referring to FIG. 10A, the robot 11 can include a spot cleaning mode(sometimes referred to as a spot coverage mode) including a star pattern1150 having pairs 155 of outward swaths 1152 and inward swaths 1153emanating from a central region 1151. Each pair 155 of swaths 1152, 1153defines an included angle α and is angularly stratified from an adjacentpair 155 of swaths 1152, 1153 by an external angle β. The repeated backand forth pattern of the star pattern 1150 can approximately mimic thecleaning pattern commonly used by operators of handheld vacuum cleaners.

To maneuver through the star pattern, the robot 11 moves in a forwarddirection of travel from a central region 1151 along an outward swath1152 and reverses direction to return to the central region 1151 alongan inward swath 1153. This process can be repeated such that the robot11 traces the star pattern 1150 corresponding to the plurality of pairs155 of swaths 1152, 1153. The star pattern 1150 can extend 180 degreesabout the central region 1151. In certain implementations, the centralregion 1151 is substantially centrally oriented relative to an area ofdetected debris 1154. In some implementations, the central region 1151is substantially peripherally oriented relative to an area of detecteddebris 1154.

The robot 11 can move through the star pattern 1150 in a clockwise orcounterclockwise direction. For example, the direction of movement ofthe robot 11 through the star pattern 1150 can be at least partly basedon a determination of the direction of debris (e.g., based on acomparison of measured signals at the first and second receivers 802A,Bof the optical detection system 800).

The length of the outward swath 1152 can be a fixed length. For example,the length of the outward swath 1152 can be between 0.5 and 5 (e.g., 1)times a dimension of the robot 11 (e.g., the fore-aft dimension of therobot). As another example, the length of the outward swath 1152 can bea function of a quantity of debris detected by the debris detectionsystem in the central region 1151 such that the length of the outwardswath 1152 is inversely proportional to the quantity of debris detectedby the debris detection system in the central region 1151 such that therobot 11 moves through a smaller star pattern 1150 in areas of higherdebris concentration.

In certain implementations, the length of the outward swath 1152 can bea variable length. For example, the robot 11 can proceed along theoutward swath 1152 until a detected quantity of debris falls below athreshold amount (e.g., indicating the perimeter of a high-debris area)

The included angle α between each outward swath 1152 and a correspondinginward swath 1153 is 0 to 45 degrees. In certain implementations, theincluded angle α is swept by turning the robot 11 (clockwise orcounterclockwise) substantially in place at the end of the outward swath1152 before reversing the direction of the robot 11 to move along theinward swath 1153. In some implementations, the value of the includedangle α is at least partly based on a quantity of debris detected by thedebris detection system (e.g., optical detection system 800). Forexample, the angle α can be at least partly determined by the amount ofdebris detected as the robot 11 moves from the central region 1151,along the outward swath 1152. In such an implementation, the detectionof a relatively large amount of debris along the outward swath 1152 canresult in a small included angle α such that there is significantoverlap in the paths cleaned by the robot along the outward and inwardswaths 1152, 1153.

In certain implementations, the external angle β between adjacent swathpairs 1155 is greater than 0 degrees and less than about 90 degrees. Theexternal angle β can be fixed relative to the included angle α. Forexample, the external angle β can be substantially equal to the includedangle α. Additionally or alternatively, the external angle β can be setaccording to one or more of the criteria described above with respect tothe included angle α.

In some implementations, the external angle β is between about −90degrees and about 90 degrees. In such implementations, the robot 11 canmove along the star pattern 1150 by moving both clockwise andcounterclockwise such that adjacent swath pairs 1155 can partially and,in some instances, completely overlap.

In certain implementations, cliff sensors 30A and 30B (shown in FIG. 1B)disposed along the respective forward and rear portions 31A,B of therobot 11 can reduce the likelihood that the robot 11 will maneuver overa cliff while executing the star pattern 1150 or another cleaningpattern including repeated backward and forward motion. For example,cliff sensors 30A disposed along the forward portion of the robot 31Acan detect a potential cliff forward of the robot 11 as the robot movesin the forward direction and cliff sensors 30B disposed along the rearportion of the robot 31B can detect a potential cliff rear of the robot11. In response to a potential cliff detected by the cliff sensors 30Aand/or cliff sensors 30B, the robot 11 can abort the spot coveragepattern and, for example, initiate avoidance and/or an escape behavior.Thus, as compared to a robot with cliff sensors along only a forwardportion, the robot 11 can execute a wider array of cleaning patternsincluding, for example, cleaning patterns that do not require the robot11 to be in a specific forward orientation.

In certain implementations, referring to FIG. 10B, the robot 11 includesa spot cleaning mode including a “cornrow” pattern 1180 having repeatedadjacent rows 1182. The robot 11 can initiate movement through thecornrow pattern 1180 at least partially based on the detection of debris1184 on the cleaning surface. Additionally or alternatively, each row1182 can extend substantially perpendicular to a detected direction ofdebris 1184 (e.g., as detected by first and second receivers 802A,B ofthe optical detection system 800).

The robot 11 can move along the cornrow pattern 1180 by moving along arow 1182 a until a quantity of detected debris (e.g., as determined bythe optical detection system 800) falls below a threshold and thenmoving the robot 11 in a substantially opposite direction along anadjacent row 1182 b and repeating this pattern for a set period of timeor until the robot 11 moves through one or more rows without detecting aquantity of debris above the threshold.

In some implementations, the robot moves along the adjacent rows 1182a,b such that the adjacent rows 1182 a,b overlap. The amount of overlapcan be a fixed amount such as, for example, a fixed multiple (e.g., onehalf) of the size of the cleaning head. Additionally or alternative, theamount of overlap between certain adjacent rows 1182 a,b can be based atleast in part on the quantity of debris 1184 detected by the robot 11,with the degree of overlap being directly proportional to the quantityof debris 1184 detected.

While the robot 11 has been described as operating in a spot coveragemode to move through the star pattern 1150 and the cornrow pattern 1180based at least in part on a detected debris signal, other types ofpatterns are additionally or alternatively possible. For example, therobot 11 can move through an inward spiral pattern, an outward spiralpattern, and/or a zig-zag pattern.

Referring to FIG. 11, in some implementations, the robot 11 includes acamera 1190 disposed toward the forward portion of the robot 11, with afield of view beyond the perimeter of the robot 11. This camera 1190 canbe in communication with the microprocessor 245 such that the movementof the robot 11 over the cleaning surface can be based at least in parton the detection of debris and/or an obstacle by the camera 1190. Forexample, the microprocessor 245 can process the signal from the camera1190 to recognize debris on the cleaning surface and maneuver the robot11 toward the debris.

Additionally or alternatively, the microprocessor 245 can process thesignal from the camera 1190 to recognize obstacles and/or debris in thevicinity of the robot 11 and maneuver the robot 11 to avoid obstaclesand/or debris larger than a specific size threshold (e.g., a value lessthan about the smallest opening defined by the cleaning head).

Referring to FIGS. 12A-12B, in some implementations, the robot 11includes robot communication terminals 1012 and the bin 50 includes bincommunication terminals 1014. Information regarding bin-full status iscommunicated from the bin 50 to the robot 11 via the communicationterminals 1012, 1014, for example. Additionally or alternatively, acliff detection signal from one or more rear cliff sensors 30B disposedon the bin 50 is communication from the bin to the robot 11 via thecommunication terminals 1012, 1014. In some implementations, the bincommunication terminals 1014 contact the corresponding robotcommunication terminals 1012 when the bin 50 is attached to the robot11. In some examples, the communication terminals 1012, 1014 includeserial ports operating in accordance with an appropriate serialcommunication standard (e.g. RS-232, USB, or a proprietary protocol).

In some examples, the robot 11 includes a demodulator/decoder 29 throughwhich power is routed from the battery 25 through the communicationterminals 1012, 1014 and to the bin 50. Bin power/communication lines1018 supply power to a vacuum motor 780, a bin microcontroller 217, andthe rear cliff sensor 30B. The bin microcontroller 217 monitors thebin-full status reported by the debris detection system 700 in the bin50, and piggybacks a reporting signal onto the power being transmittedover the bin-side lines 1018. The piggybacked reporting signal is thentransmitted to the demodulator/decoder 29 of the robot 11. Themicroprocessor 245 of the robot 11 processes the bin full indicationfrom the reporting signal piggybacked onto the power lines 1018, forexample.

In certain implementations, the bin microcontroller 217 monitors thebin-full status reported by the debris detection system 700 in the bin50 (e.g., independently of a robot controller), allowing the bin 50 tobe used on robots without a debris detection system 700. A robotsoftware update may be required for the bin upgrade.

In some implementations, as shown in FIG. 12A, the bin 50 includes a binpower source 1013 (e.g., a battery) in electrical communication with thebin microcontroller 217, the vacuum motor 780, a bin-full indicator1015, and/or a rear cliff sensor 30B disposed on the bin 50. The binmicrocontroller 217 may control power to the vacuum motor 780, based atleast in part on the bin-full status reported by the debris detectionsystem 700. For example, the bin microcontroller 217 may disable powerto the vacuum motor 780 upon detection of a bin-full condition reportedby the debris detection system 700. Additionally or alternatively, thebin microcontroller 217 may control the status of the bin-full indicator1015 (e.g., an LED) to provide the user with a visual indication of thestatus of the bin (e.g., the bin is full if the bin-full indicator 1015is illuminated). Powering the bin-full indicator 1015 with the bin powersource 1013 allows the bin-full indicator 1015 to remain illuminatedwhile the bin 50 is disengaged from the robot 11 (e.g., while the bin 50is being emptied).

Referring to FIG. 12B, in some implementations, the robot 11 includes areceiver 1020 (e.g., an infrared receiver) and the bin 50 includes acorresponding emitter 1022 (e.g., an infrared emitter). The emitter 1022and receiver 1020 are positioned on the bin 50 and robot 11,respectively, such that a signal transmitted from the emitter 1022reaches the receiver 1020 when the bin 50 is attached to the robot 11.For example, in implementations in which the receiver 1020 and theremitter 1022 are infrared, the emitter 1022 and the receiver 1020 arepositioned relative to one another to facilitate line-of-sightcommunication between the emitter 1022 and the receiver 1020. In someexamples, the emitter 1022 and the receiver 1020 both function asemitters and receivers, allowing bi-directional communication betweenthe robot 11 to the bin 50. In some examples, the robot 11 includes anomni-directional receiver 13 on the chassis 31 and configured tointeract with a remote virtual wall beacon 1050 that emits and receivesinfrared signals. A signal from the emitter 1022 on the bin 50 isreceivable by the omni-directional receiver 13 and/or the remote virtualwall beacon 1050 to communicate a bin fullness signal. If the robot 11was retrofitted with the bin 50 and received appropriate software, theretrofitted bin 50 can direct the robot 10 to return to a maintenancestation (e.g., maintenance station 1250 in FIGS. 15A,B) for servicingwhen the bin 50 is full. While infrared communication between the robot11 and the bin 50 has been described, one or more other types ofwireless communication may additionally or alternatively be used toachieve such wireless communication. Examples of other types of wirelesscommunication between the robot 11 and the bin 50 includeelectromagnetic communication and radiofrequency communication.

Referring to FIGS. 13A-13D, in some implementations, the bin 50 includesa bin-full indicator 1130. In some examples the bin-full indicator 1130includes visual indicator 1132 such as an LED (FIG. 13B), LCD, a lightbulb, a rotating message wheel (FIG. 13C) or a rotating color wheel, orany other suitable visual indicator. The visual indicator 1132 maysteadily emit light, flash, pulse, cycle through various colors, oradvance through a color spectrum in order to indicate to the user thatthe bin 50 is full of debris, inter alia. The indicator 30 may includean analog display for indicating the relative degree of fullness of thebin 50. For example, the bin 50 includes a translucent window over topof a rotatable color wheel. The translucent window permits the user toview a subsection of the color wheel rotated in accordance with a degreeof fullness detected in the bin 50, for example, from green (empty) tored (full). In some examples, the indicator 30 includes two or more LEDswhich light up in numbers proportional to bin fullness, e.g., in a barpattern. Alternatively, the indicator 1030 may be an electrical and/ormechanical indicator, such as a flag, a pop up, or message strip, forexample. In other examples, the bin-full indicator 1130 includes anaudible indicator 1134 such as a speaker, a beeper, a voice synthesizer,a bell, a piezo-speaker, or any other suitable device for audiblyindicating bin-full status to the user. The audible indicator 1134 emitsa sound such as a steady tone, a ring tone, a trill, a buzzing, anintermittent sound, or any other suitable audible indication. Theaudible indicator 1134 modulates the volume in order to draw attentionto the bin-full status (for example, by repeatedly increasing anddecreasing the volume). In some examples, as shown in FIG. 13D, theindicator 1130 includes both visual and audible indicators, 1132 and1134, respectively. The user may turn off the visual indicator 1132 oraudible indicator 1134 without emptying the bin 50. In someimplementations, the bin-full indicator 1130 is located on the robotbody 31 or shell 6 of the robot 11.

Referring to FIGS. 14A-14B, in some implementations, the bin 50wirelessly transmits a signal to a remote indicator 1202 (via atransmitter 1201, for example), which then indicates to a user that thebin is full using optical (e.g. LED, LCD, CRT, light bulb, etc.) and/oraudio output (such as a speaker 1202C). In one example, the remoteindicator 1202 includes an electronic device mounted to a kitchenmagnet. The remote indicator 1202 may provide (1) generalized robotmaintenance notifications (2) a cleaning routine done notification (3)an abort and go home instruction, and (4) other control interaction withthe robot 10 and/or bin 50.

An existing robot 11, which does not include any communication path orwiring for communicating with a bin-full sensor system 700 on the bin50, is nonetheless retrofitted with a bin 50 including a bin-full sensorsystem 700 and a transmitter 1201. “Retrofitting” generally meansassociating the bin with an existing, in-service robot, but for thepurposes of this disclosure, at least additionally includes forwardfitting, i.e., associating the bin with a newly produced robot in acompatible manner. Although the robot 11 cannot communicate with thebin-full sensor system 700 and may possibly not include any program orbehavioral routines for responding to a bin-full condition, the bin 50may nonetheless indicate to a user that the bin 50 is full bytransmitting an appropriate signal via the transmitter 1201 to a remoteindicator 1202. The remote indicator 1202 may be located in a differentroom from the robot 11 and receives signals from the bin 50 wirelesslyusing any appropriate wireless communication method, such as IEEE801.11/WiFi, BlueTooth, Zigbee, wireless USB, a frequency modulatedsignal, an amplitude modulated signal, or the like.

In some implementations, as shown in FIG. 14B, the remote indicator 1202is a magnet-mounted unit including an LED 1204 that lights up or flasheswhen the bin 50 is full. In some examples, as shown in FIG. 14C, theremote indicator 1202 includes an LCD display 1206 for printing amessage regarding the bin full condition and/or a speaker 1208 foremitting an audible signal to the user. The remote indicator 1202 mayinclude a function button 1210, which transmits a command to the robot11 when activated. In some examples, the remote indicator 1202 includesan acknowledge button 1212 that transmits an appropriate command signalto the mobile robot 20 when pushed. For example, when a bin-full signalis received, the LCD display 1206 may display a message indicating tothe user that the bin is full. The user may then press the button 1212,causing a command to be transmitted to the robot 11 that in turn causesthe robot 11 to navigate to a particular location. The user may thenremove and empty the bin 50, for example.

In some examples, the remote indicator 1202 is a table-top device or acomponent of a computer system. The remote indicator 1202 may beprovided with a mounting device such as a chain, a clip or magnet on areverse side, permitting it to be kept in a kitchen, pendant, or on abelt. The transmitter 1201 may communicate using WiFi or other homeradio frequency (RF) network to the remote indicator 1202 that is partof the computer system 1204, which may in turn cause the computer systemto display a window informing the user of the bin-full status.

Referring to FIG. 14D, when the optical detection system 800 determinesthat the bin 50 is full and/or when the microprocessor 245 determinesthat a state-of-charge of the battery 25 has fallen below a threshold,the robot 11, in some examples, maneuvers to a maintenance station 1250(e.g., a dock) for servicing. Maneuvering the robot 11 to themaintenance station 1250 is described in further detail below.

The robot 11 releasably engages with the maintenance station 1250. Insome examples, the maintenance station 1250 automatically evacuates thebin 50 (e.g. via a vacuum tube connecting to an evacuation port 80, 305,380, 415, 420, 425, 430 of the bin 50). Additionally or alternatively,the maintenance station 1250 charges the battery 25. For example, themaintenance station 1250 can charge the battery 25 through releasableengagement with at least one charging terminal 72. In some examples, thecharging terminal 72 is disposed along a bottom portion of the robot 11.Additionally or alternatively, the charging terminal 72 can be disposedalong a top portion and/or a side portion of the robot 11. The at leastone charging terminal 72 can be a contact terminal.

If the cleaning head 40 is full of filament build up, the robot 11 mayautomatically discharge the cleaning brush/flapper 60, 65 for eitherautomatic or manual cleaning. The brush/flapper 60, 65 may be fed intothe maintenance station 1250, either manually or automatically, whichstrips filament and debris from the brush/flapper 60, 65.

Referring to FIGS. 15-16, in some examples, the maintenance station 1250emits a signal 1252 (e.g., a single signal, multiple signals, ormultiple overlapping signals). The signal 1252 can be, for example, oneor more optical signals (e.g., infrared) and/or acoustic signals. Therobot 11 includes a receiver 15 for receiving the signal 1252. Otherdetails and features of signal emission by the maintenance station 1250and signal reception by the robot 11 are disclosed in U.S. Pat. No.7,332,890, entitled “Autonomous Robot Auto-Docking and Energy ManagementSystems and Methods,” the entire contents of which are incorporatedherein by reference.

As the robot 11 moves over a cleaning surface 1, the receiver 15 canreceive the signal 1252 emitted by the maintenance station 1250 as therobot 11 moves along a path 1254 (e.g., in a bounce mode). The robot 11can detect the time t1-t7 associated with each change in the signal1252, with each change in the signal 1252 representing respectivemovement of the robot 11 into and out of the signal 1252. For example,the robot 11 detects movement out of the signal 1252 at t1 and detectsmovement into the signal 1252 at t2. Similarly, the robot 11 detectsmovement out of the signal 1252 at t3 and detects movement into thesignal 1252 at t4. As described below, the microprocessor 245 of therobot 11 can seek the maintenance station 1250 based at least in part onthe elapsed time between t1 and t2, t3 and t4, etc. For the sake ofclarity of explanation, seven times associated with change in the signal1252 are shown in FIG. 15B. However, it should be appreciated that therobot can detect any number of times.

In some implementations, seeking 1300 the maintenance station 1250 caninclude maneuvering 1302 the robot 11 over the cleaning surface 1 alongpath 1254, detecting 1304 a first change in a signal emitted from themaintenance station 1250, detecting 1306 a second change in the signalemitted from the maintenance station 1250, and determining 1308 theprobability that the robot will find the dock in a period of time. Thedetermination 1308 of the probability that the robot will find the dockin a period of time is based at least in part on the elapsed timebetween the detected 1304 first change in the signal and the detected1306 second change in the signal. This determination 1308 can reduce,for example, the likelihood that the robot 11 will become stranded onthe cleaning surface 1 without enough power to return to the maintenancestation 1250. In certain implementations, the robot 11 seeks 1300 themaintenance station 1250 continuously. In some implementations, therobot 11 seeks 1300 the maintenance station 1250 periodically.Additionally or alternatively, the robot 11 can seek 1300 themaintenance station 1250 upon detection that a state-of-charge of thebattery 25 is below a threshold (e.g., below about 50 percent).

Maneuvering 1302 the robot 11 over the cleaning surface can includemaneuvering the robot 11 while one or more other behaviors are beingexecuted. For example, maneuvering 1302 can include moving the robot 11over the cleaning surface 1 in a bounce mode, a spot coverage mode, anescape mode, a migration mode, etc. Additionally or alternatively,maneuvering 1302 the robot 11 over the cleaning surface 1 can bedetermined by an arbiter. Details and features of such an arbiter aredescribed in U.S. Pat. No. 7,388,343, entitled “Method and System forMulti-Mode Coverage for an Autonomous Robot,” the entire contents ofwhich are incorporated herein by reference.

Detecting 1304 the first change in the signal emitted from themaintenance station 1250 includes receiving (e.g., by receiver 15) thesignal 1252 emitted from the maintenance station 1250. The detected 1304first change in the signal can include detecting a change from receivingno signal to receipt of a signal and/or detecting a change from receiptof a signal to receipt of no signal. In some implementations, detecting1304 the first change in the signal includes detecting an encodedsignal. For example, the signal can be encoded to identify themaintenance station 1250 associated with the robot 11 such that therobot 11 does not seek a maintenance station 1250 that is not associatedwith the robot 11.

Detecting 1306 the second change in the signal emitted from themaintenance station 1250 includes receiving (e.g., by receiver 15) thesignal 1252 emitted from the maintenance station 1250. Detecting 1306the second change in the signal 1252 temporally follows detecting 1304the first change in the signal such that there is an elapsed timebetween the detected 1304 first change in the signal and the detected1306 second change in the signal.

Determining 1308 the probability that the robot will find themaintenance station 1250 is based at least in part on the elapsed timebetween detecting 1304 the first change in the signal and detecting 1306the second change in the signal. The elapsed time between detecting 1304the first change in the signal and detecting 1306 the second change inthe signal represents the time between maintenance station 1250sightings by the robot 11. In some implementations, the elapsed time isused to update a probability distribution based at least in part on theelapsed time and/or previously determined elapsed times. For example,the elapsed time between t6 and t5 can be used to update a probabilitydistribution including the elapsed time between t4 and t3 and theelapsed time between t2 and t1.

The probability distribution can be used to estimate the probabilitythat the robot 11 will reach the maintenance station 1250 within aperiod of time (e.g., a specified period of time or a variable period oftime). For example, the probability distribution can be used to estimatethe probability that the robot 11 will reach the maintenance station1250 within five minutes.

Additionally or alternatively, the probability distribution can be usedto determine the amount of time required for the robot 11 to reach themaintenance station 1250 with a certain probability. For example, theprobability distribution can be used to estimate the amount of timerequired for the robot 11 to reach the maintenance station 1250 withgreater than 75 percent probability. In some examples, the amount oftime required for the robot 11 to reach the maintenance station 1250with a certain probability can be the time allotted to allow the robot11 to find the maintenance station 1250. Thus, in one example, if theestimated time required for the robot to reach the maintenance station1250 with greater than 95 percent probability is five minutes and a 95percent success rate in finding the maintenance station 1250 is desired,the robot 11 will begin attempting to find the maintenance station 1250when the remaining battery life 25 is five minutes. To allow for afurther margin of safety, the robot 11 can reduce power consumption ofthe battery 25 by reducing, for example, the amount of power to thecleaning head 40 during the allotted time.

In some implementations, the probability distribution of elapsed timesis a non-parametric model. For example, the non-parametric model can bea probability distribution histogram of probability as a function ofelapsed time. The elapsed time ranges used for resolution of thehistogram can be fixed values (e.g., about 5 second to about two minuteintervals).

In certain implementations, the probability distribution of elapsedtimes is a parametric model. For example, the parametric model can be aPoisson distribution in which a successful outcome is an outcome inwhich the robot 11 reaches the maintenance station 1250 within a periodof time and a failure is an outcome in which the robot 11 does not reachthe maintenance station 1250 within a period of time. The mean of thePoisson distribution can be estimated, for example, as the arithmeticmean of a plurality of elapsed time measurements. From the Poissondistribution, the probability that the robot 11 will reach themaintenance station 1250 within a period of time can be determined. Forexample, the Poisson distribution can be used to determine theprobability that the robot 11 will reach the maintenance station 1250within five minutes. As an additional or alternative example, thePoisson distribution can be used to determine the amount of timerequired for the robot 11 to reach the maintenance station 1250 with acertain probability (e.g., a probability of greater than 75 percent).

In some implementations, determining 1308 the probability that the robot11 will find the maintenance station 1250 can include determining theprobability that power available from the battery 25 carried by therobot 11 will be depleted before the robot 11 can find the maintenancestation 1250. For example, the amount of time corresponding to theremaining power available from the battery 25 can be estimated based onthe rate of power consumption of the robot 11 in the current mode ofoperation. The probability that the robot 11 will reach the maintenancestation 1250 within the remaining battery time can be determined, forexample, using the non-parametric and/or the parametric models discussedabove.

If the robot 11 is removed from the cleaning surface 11, the elapsedtimes between successive sightings of the maintenance station 1250 maynot be representative of the amount of time required for the robot 11 tofind the maintenance station 1250. Thus, in some implementations,seeking 1300 the maintenance station 1250 includes ignoring a change inthe detected signal following detection that the robot 11 was removedfrom the surface 1. For example, if the robot 11 was removed from thesurface 1 between t1 and t2, the detected 1304 first change in thesignal 1252 corresponding to t1 is ignored and the detected 1306 secondchange in the signal 1252 is also ignored such that the next elapsedtime is determined as the difference between t4 and t3. In certainimplementations, detecting that the robot has been removed from thesurface includes receiving a signal from one or more sensors (e.g.,cliff sensors 30A and 30B and/or proximity sensors 70) carried by therobot 11. Additionally or alternatively, wheels 45 can be biased-to-dropand detecting that the robot has been removed from the surface caninclude detecting that the wheels 45 have dropped. Details of suchbiased-to-drop wheels 45 and detection of dropped wheels is disclosed inU.S. Pat. No. 7,441,298, entitled “Coverage Robot Mobility,” the entirecontents of which are incorporated herein by reference.

Referring to FIGS. 17-18, the maintenance station 1250 emits a firstsignal 1252′ (e.g., a single signal, multiple signals, or multipleoverlapping signals) and a second structure 1258 emits a second signal1258. The second structure 1258 can be a lighthouse (e.g., a navigationbeacon), a gateway marker, a second maintenance station, etc. The robot11 moves on the cleaning surface 1, along a path 1260 such that therobot 11 intersects the signal 1252′ emitted by the maintenance station1250 and intersects the signal 1258 emitted by the second structure1256. The robot 11 intersects the signal 1252′ at t1′, t4′, and t5′, andthe robot 11 intersects the signal 1258 at t2′ and t3′. The secondstructure 1256 can act as a landmark to assist in the prediction offinding the maintenance station 1250. For example, as described below,the time between sighting the second structure 1256 and sighting themaintenance station 1250 can be used to predict the amount of timeneeded to find the dock given that the second structure 1256 was justseen.

In some implementations, seeking 1400 the maintenance station 1250includes maneuvering 1402 the robot over the cleaning surface 1,detecting 1404 the maintenance station 1250, detecting 1406 the secondstructure 1256, and determining 1408 the probability that the robot willfind the maintenance station 1250 within a period of time. In someimplementations, the signal 1252′ from the maintenance station 1250differs from the signal 1258 emitted from the second structure 1256(e.g., encoded differently and/or having different wavelengths). Seeking1400 can allow the robot 11 to navigate by choosing actions that providethe best chance of moving from one landmark to the next, stringingtogether a path that ends at a goal location, such as the maintenancestation 1250.

Detecting 1404 the maintenance station 1250 includes detecting a changein the received signal 1252′ emitted by the maintenance station 1250. Attime t1 ‘, for example, the change in the received signal 1252’ is achange from receiving the signal 1252′ to not receiving the signal1252′. As another example, at time t4′, the change in the receivedsignal 1252′ is a change from not receiving the signal 1252′ toreceiving the signal 1252′.

Detecting 1406 the second structure 1256 includes detecting a change inthe received signal 1256 emitted by the second structure 1256. At timet2′, for example, the change in the received signal 1258 is a changefrom not receiving the signal 1258 to receiving the signal 1258. Asanother example, at time t3′, the change in the received signal 1258 isa change from receiving the signal 1258 to not receiving the signal1258.

Determining 1408 the probability that the robot 11 will find themaintenance station 1250 within a period of time is based at least inpart upon the elapsed time between detecting 1404 the maintenancestation 1250 and detecting 1406 the second structure 1256. For example,the elapsed time is the difference between t2′ and t1′ and theprobability determination is the probability that the robot 11 will findthe maintenance station 1250 given that the second structure 1256 hasjust been detected. The determination 1408 of the probability that therobot 11 will find the maintenance station 1250 within a period of timecan be analogous to the determination 1308 discussed above.

In some implementations, the maintenance station 1250 is a firstlighthouse (e.g., when the battery 25 is fully charged) and the secondstructure 1256 is a second lighthouse such that the robot 11 moves alongthe cleaning surface 1 based on relative positioning to the maintenancestation 1250 and/or to the second structure 1256.

FIGS. 19A-G show another implementation of an autonomous roboticcleaner. Features identified by reference symbols including a prime areanalogous to features identified by corresponding unprimed referencesymbols in the implementations described above, unless otherwisespecified. Thus, for example, robot 11′ is analogous to robot 11 and bin50′ is analogous to bin 50.

A bin guide 33 defines at least a portion of a receiving volume 37defined by the robot body 31′. Bin 50′ is movable (e.g., slidable) alongbin guide 33 to lock into place (e.g., as described below) such thatmouth 53′ of bin 50′ aligns with a top portion of the receiving volume37. For example, such alignment is shown in FIG. 8A, FIGS. 19C, and 19F.FIG. 19C is a cross-sectional view taken through robot 11′, along thereceiving volume 37, with bin 50′ inserted in the receiving volume 37.Accordingly, as shown in FIG. 19C, for example, debris moves pastinfrared array assemblies 810 disposed along a top portion of receivingvolume 37 and into mouth 53′ defined by bin 50′. Such movement is shownschematically in FIG. 19F, for example, in which the position ofinfrared array assembly 810 (which is disposed along the receivingvolume 37 of the robot 11′ and, thus, represented as a dashed line inFIG. 19F) is shown relative to mouth 53′ defined by bin 50′.

Each infrared array assembly 810 includes an emitter array (firstemitter array 804A′ or second emitter array 804B′, as shown in FIG.19C), with each respective emitter array including two light sources806′. Each infrared array assembly 810 also includes a receiver (firstreceiver 802A′ or a second receiver 802B′, as shown in FIG. 19C) and afilter 812 disposed between the receiving volume 37 and the respectiveemitter array and receiver of the infrared array assembly 810. Eachfilter 812 can be an infrared transparent daylight filter.

Although each infrared array assembly 810 is shown as disposed alongreceiving volume 37 defined by robot body 31′, each infrared arrayassembly 810 can be disposed on bin 50′. Whether the infrared arrayassembly 810 is disposed on the receiving volume 37 or the bin 50′, thefirst and second receivers 802A′, 802B′ and the first and second emitterarrays 804A′, 804B′ can be substantially evenly spaced across the mouth53′ on each horizontal side of the mouth 53′ to substantially spanhorizontal and vertical dimensions of the mouth 53′ with emitted lightfrom the array assemblies 810.

Robot 11′ includes a dust bin 50′ for collecting debris while the robot11′ is in operation. The dust bin 50′ is releasably detachable from therobot 11′ (e.g., releasably detachable from the robot body 31′) to allowdebris to be removed from the dust bin 50′ and/or to allow a filter 811carried by the dust bin 50′ to be replaced. The dust bin 50′ can beremoved from robot 11′ by moving a release 819 (e.g., depressing therelease 819 and/or lifting the release 819) that moves a latch 809 suchthat the dust bin 50′ can be slidably removed from the robot 11′. Insome implementations, release 819 can include one or more lights (e.g.,lights indicative of an operating mode of the robot 11′) and/or one ormore proximity sensors. In certain implementations, release 819 sensesthe position of the latch 809 such that release 819 provides anindication of the position of the bin 50′ (e.g., an indication that thebin 50′ is not fully engaged with the robot 11′).

The bin 50′ includes a barrier 55 which extends horizontally across thewidth of the bin 50′ and extends vertically along at least a portion ofthe bin 50′ such that the barrier 55 defines at least a portion of ahorizontal bottom portion of the mouth 53′. In some implementations,barrier 55 defines at least a portion of a compartment that retainsdebris settled at the bottom of the bin 50′ when the bin is in situ inthe robot 11′. In certain implementations, at least a portion of thebarrier 55 is a door (e.g., a hinged door and/or a slidable door) thatis movable to allow access to debris stored in the bin 50′. In someimplementations, the barrier 55 is rigidly fixed relative to the mouth53′ and access to debris is obtained through one or more doors formingpart of a side wall, a bottom wall, or a rear wall of the bin 50′.

In some implementations, the vertical dimension of the mouth 53′ issubstantially ½ or less of the combined height of the barrier 55 and thevertical dimension of the mouth 53′. Accordingly, in implementations inwhich the height of the bin 50′ is defined approximately by the combinedvertical dimensions of the mouth 53′ and the barrier 55, the verticaldimension of the barrier 55 can be greater than the vertical dimensionof the mouth 53′. These relative dimensions of the barrier 55 to themouth 53′ can facilitate storage of a large amount of debris in the bin50′ while retaining the profile of the robot 11′ during use.

Although the mouth 53′ and the barrier 55 are shown as extendingsubstantially across the entire width of the bin 50′, otherconfigurations are also possible. For example, the mouth 53′ can extendabout ⅔ of the width of the bin 50′ or less while the barrier 55 extendssubstantially across the entire width of the bin 50′ such that the widthof the barrier 55 is at least ⅓ greater than the width of the mouth 53′.These relative dimensions of the barrier 55 to the mouth 53′ canfacilitate storage of a large amount of debris in the bin 50′ whileretaining the profile of the robot 11′ during use.

Although the bin 50′ is shown as defining a mouth 53′ having a singleopening, other implementations are also possible. For example, the bin50′ may define a mouth having multiple openings which can facilitateincreasing turbulence along the flow path 819 (FIG. 19F) and/orfacilitate breaking up large pieces of debris as it moves along the flowpath 819. For example, the bin 50′ may define a mouth having twoopenings horizontally spaced apart from one another. More generally, asused herein, the term mouth refers to the total open area through whichdebris passes into the bin 50′ during operation.

The bin 50′ includes a protrusion 807 disposed toward an end portion ofthe bin 50′ that engaged with the robot 11′. The protrusion 807 canengage with robot 11′ to reduce the likelihood of damage to portions ofthe bin 50′ as the bin 50′ is slid into engagement with the robot 11′.For example, the protrusion 807 can reduce the likelihood of damage tothe door 54′ and/or to the release 819 as the bin 50′ is slid into therobot 11′. Additionally or alternatively, the protrusion 807 canfacilitate alignment of the latch 809 for securing the bin 50′ to therobot 11′.

The bin 50′ further includes a filter 811, a motor 815, and an impeller817. During use, a fluid stream 819 (e.g., debris carried in air) isdrawn into the bin 50′ by negative pressure created by rotation of theimpeller 817 driven by the motor 815. The fluid stream 819 moves pastthe optical detection system 800′ such that debris detection andbin-full detection can be carried out as described above. The fluidstream 819 moves through a filter 811 such that the debris is separatedfrom the air, with the debris remaining in the bin 50′ (e.g., in aportion of the bin 50′ at least partially defined by barrier 55) and theair exiting the bin 50′ through an exhaust 813 defined by the bin 50′.

An optical detection system 800′ is similar to optical detection system800 and operates to detect debris and bin-full conditions in a manneranalogous to the debris and bin-full detection described above withrespect to FIGS. 8A-8E. In general, the views shown in FIGS. 8A-8Ecorrespond to the front view of the bin 50′ shown in FIG. 19C. As shownin FIG. 19C, the mouth 53′ defined by the bin 50′ extends along onlypart of the vertical dimension of the bin 50′. Thus, to furtherillustrate the correspondence in structure between the bin 50 shown inFIG. 8A and the bin 50′ shown in FIG. 19C, the position of the mouth 53′is shown as dashed line in FIG. 8A.

Accordingly, it should be appreciated that the detection of the debris48 shown in FIG. 8B is analogous to the debris detection of debrisentering bin 50′ through mouth 53′, along path 819. Similarly, it shouldbe appreciated that the bin-full detection as a result of theaccumulation 49 of debris shown in FIG. 8C is analogous to the bin-fulldetection of an accumulation of debris in a compartment defined by thebin 50′. Likewise, it should be further appreciated that the detectionof asymmetric debris accumulation shown in FIGS. 8D and 8E is analogousto the detection of asymmetric debris accumulation in a compartmentdefined by the bin 50′.

Other details and features combinable with those described herein may befound in U.S. patent application Ser. No. 11/751,267, filed May 21,2007, entitled Coverage Robots and Associated Cleaning Bins, and U.S.patent application Ser. No. 10/766,303, filed Jan. 28, 2004, entitledDebris Sensor for Cleaning Apparatus, now U.S. Pat. No. 6,956,348. Theentire contents of each of the aforementioned applications are herebyincorporated by reference in their entirety.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made without departingfrom the spirit and scope of the disclosure. Accordingly, otherimplementations are within the scope of the following claims.

What is claimed is:
 1. A debris monitoring system comprising: areceptacle defining an opening to receive debris into the receptacle,the opening having a top portion and a bottom portion, the top portionabove the bottom portion as debris is received into the receptacle; afirst and a second emitter, each arranged to emit a signal across atleast a portion of the opening; and a first receiver proximate to thefirst emitter to receive reflections of the signal emitted by the firstemitter, the first receiver disposed along a top portion of the openingand toward the opening to receive an unreflected portion of the signalemitted by the second emitter across the largest dimension of theopening.
 2. The debris monitoring system of claim 1 wherein the openingis substantially rectangular and the first receiver and the secondreceiver are substantially diagonally opposed to one another across theopening.
 3. The debris monitoring system of claim 1 wherein the firstand second emitter are arranged relative to one another such that therespective signals emitted by the first and second emitters intersectalong at least a portion of the opening.
 4. The debris monitoring systemof claim 1 wherein the opening is defined in a substantially verticalplane as debris is received into the receptacle.
 5. The debrismonitoring system of claim 1 wherein the first receiver is arrangedabout 1 inches to about 8 inches from the second emitter.
 6. The debrismonitoring system of claim 1 wherein the first receiver is less thanabout 0.25 inches from the first emitter.
 7. The debris monitoringsystem of claim 1 wherein the ratio of the distance between the firstreceiver and the second emitter to the distance between the firstreceiver and the first emitter is about 4 to about
 100. 8. The debrismonitoring system of claim 1 wherein the receptacle is releasablyengageable with a housing configured to support the receptacle as debrisis received through the opening of the receptacle.
 9. The debrismonitoring system of claim 8 wherein the first and second emitters andthe first receiver are each supported on the housing and the receptacleis movable relative to the first and second emitters and the firstreceiver.
 10. The debris monitoring system of claim 8 wherein the firstand second emitters and the first receiver are each supported on thereceptacle.
 11. The debris monitoring system of claim 10 furthercomprising a controller supported on the housing, wherein the first andsecond emitters and the first receiver are each in wirelesscommunication with the controller.
 12. The debris monitoring system ofclaim 11 wherein the wireless communication comprises infraredcommunication.
 13. A debris monitoring system comprising: a receptacledefining an opening to receive debris into the receptacle; a pluralityof first emitters and a plurality of second emitters, each emitter ofeach plurality of emitters arranged to emit a signal across at least aportion of the opening; a first receiver proximate to the plurality offirst emitters to receive reflections of the signal emitted by each ofthe plurality of first emitters and the first receiver disposed towardthe opening to receive an unreflected portion of the signal emitted byeach of the plurality of second emitters across at least a portion ofthe opening; and a second receiver proximate to the plurality of secondemitters to receive reflections of the signal emitted by each of theplurality of second emitters and the second receiver disposed toward theopening to receive an unreflected portion of the signal emitted by eachof the plurality of first emitters across at least a portion of theopening.
 14. The debris monitoring system of claim 13 further comprisinga controller configured to pulse the plurality of first emitters on andoff and to pulse the plurality of second emitters on and off.
 15. Thedebris monitoring system of claim 14 wherein the controller is furtherconfigured to sample of each of the first and second receiverssynchronously such that a first sample of each receiver is taken whenthe plurality of first emitters and the plurality of second emitters areoff, a second sample of each receiver is taken when the plurality offirst emitters is on and the plurality of second emitters is off, and athird sample of each receiver is taken when the plurality of firstemitters is off and the plurality of second emitters is on.
 16. Thedebris monitoring system of claim 13 wherein the plurality of firstemitters and the plurality of second emitters are arranged relative toone another such that the signals emitted by the plurality of firstemitters intersect the signals emitted by the plurality of secondemitters, the intersection being along at least a portion of theopening.
 17. The debris monitoring system of claim 16 wherein theplurality of first emitters and the plurality of second emitters arearranged relative to one another such that the signals emitted by theplurality of first emitters intersect the signals emitted by theplurality of second emitters along a line substantially bisecting theopening.
 18. The debris monitoring system of claim 13 wherein theplurality of first emitters and the plurality of second emitters arespaced relative to one another such that the signals emitted by theplurality of first emitters and the plurality of second emitters spansubstantially all of the area of the opening when all of the emittersfrom each of the plurality of first and second emitters are on.